Marine Biological Laboratory Library

Woods Hole, Massachusetts

Gift of F. R. Lillie estate - 1977

A MANUAL

OF

HUMAN PHYSIOLOGY.

A MANUAL OF

HUMAN PHYSIOLOGY,

INCLUDING

HISTOLOGY AND MICROSCOPICAL ANATOMY;

WITH SPECIAL REFERENCE TO THE REQUIREMENTS OF

PRACTICAL MEDICINE.

BY

DR. L. L A N D O I S,

PROFESSOR OF PHYSIOLOGY AND DIRECTOR OF THE PHYSIOLOGICAL INSTITUTE,
UNIVERSITY OF GREIFSWALD.

TRANSLATED FROM THE FOURTH GERMAN EDITION.

WITH ADDITIONS BY

WILLIAM STIRLING, M.D., Sc.D.,

REGIUS PROFESSOR OF THE INSTITUTES OF MEDICINE OR PHYSIOLOGY IN THE UNIVERSITY OF ABERDEEN.

176 IT_,ljTJSTK,-A,TXOlTS.

VOL. I.

PHILADELPHIA:

P. BLAKISTON, SON, AND COMPANY,
1012 WALNUT STREET.

1885.
\All Rights Reserved.\

TO

SIR JOSEPH LISTER, BARONET,

M.D., D.C.L., LL.D., F.E.SS. (LOND. AND EDIN.),

PEOFESSOE OF CLINICAL SURGERY IN KING'S COLLEGE, LONDON, SURGEON-EXTRAORDINARY TO THE QCEEX;
FORMERLY REGIUS PROFESSOR OF CLINICAL SUHGEEY IN THE UNIVERSITY OF EDINBURGH.

IN ADMIRATION OF

%^t Pan oi jSmttJt*,

WHOSE BRILLIANT DISCOVERIES HAVE REVOLUTIONISED
MEDICAL PRACTICE, AND CONTRIBUTED INCALCULABLY TO THE

WELL-BEING OP MANKIND;
AND IN GRATITUDE TO

WHOSE NOBLE EARNESTNESS IN INCULCATING

THE SACREDNESS OF HUMAN LIFE
STIRRED THE HEARTS OF ALL WHO HEARD HIM :

cTbis Modi is rrspcttfulln Qcbitutcir
BY HIS FORMER PUPIL,

THE TRANSLATOR.

PKEFACE.

THE fact that Prof essor LANDOIS' " Lehrbuch der Physiologie des Menschen"
has already passed through Four large Editions since its first appearance
in 1880, shows that in some special way it has met the wants of
Students and Practitioners in Germany. The characteristic which
has thus commended the work will be found mainly to lie in its
eminent practicality; and it is this consideration which has induced

-/. it f

me to undertake the task of putting it into an English dress for
English readers.

Landois' work, in fact, forms a Bridge between Physiology and the
Practice of Medicine. It never loses sight of the fact that the Student
of to-day is the practising Physician of to-morrow. Thus, to every
Section is appended after a full description of the normal processes
a short rdsum6 of the pathological variations, the object of this being to
direct the attention of the Student, from the outset, to the field of his
future practice, and to show him to what extent pathological processes
are a disturbance of the normal activities.

In the same Avay, the work offers to the busy physician in practice a
ready means of refreshing his memory on the theoretical aspects of
Medicine. He can pass backwards from the examination of pathological
phenomena to the normal processes, and, in the study of these, find new
indications and new lights for the appreciation and treatment of the
cases under consideration.

With this object in view, all the methods of investigation which may
with advantage lie used by the Practitioner, are carefully and fully
described ; and Histology, also, occupies a larger place than is usually
assigned to it in Text-books of Physiology.

A word as to my own share in the present version :

(1.) In the task of translating, I have endeavoured throughout to
convey the author's meaning accurately, without a too rigid adherence
to the original. Those who from experience know something of the
difficulties of such an undertaking will be most ready to pardon any
shortcomings they may detect.

Viil PREFACE.

(2.) Very considerable additions have been made to the Histological,
and also (where it has seemed necessary) to the Physiological sections.
All such additions are enclosed within square brackets [ ]. I have to
acknowledge my indebtedness to many valuable Papers in the various
Medical Journals British and Foreign and also to the Histological
Treatises of Cadiat, Eanvier, and Klein; Quain's Anatomy, vol. n.,
ninth edition; Hermann's llandbucli der Physiologic; and the Text-
books on Physiology, by Rutherford, Foster, and Kirkes ; Gamgee's
Physiological Chemistry; Ewald's Digestion; and Roberta's Digestive
Ferments.

(3.) The Illustrations have been increased in number from 106
in the Fourth German Edition to 176 in the English version. These
additional Diagrams, with the sources whence derived, are distinguished
in the List of Woodcuts by an asterisk.

There only remains for me now to express my thanks to all who
have kindly helped in the progress of the work, either by furnishing
Illustrations or otherwise especially to Drs. Byrom Bramwell,
Dudgeon, Lauder Brunton, and Knott ; Mr. Hawksley; Professors
Hamilton and M'Kendrick; to my esteemed teacher and friend,
Professor Ludwig, of Leipzic ; and, finally, to my friend, Mr. A. W.
Robertson, M.A., formerly Assistant "Librarian in the University, and
now Librarian of the Aberdeen Public Library, for much valuable
assistance while the work was passing through the press.

The Second Part will, it is hoped, be issued early in 1885.

In conclusion and forgetting for the moment my own connection
with it I heartily commend the work per se to the attention of
Medical Men, and can wish for it no better fate than that it may
speedily become as popular in this country as it is in its Fatherland.

WILLIAM STIRLING.

ABERDEEN UNIVERSITY,
November, 1884.

GENERAL CONTENTS.

INTRODUCTION.

PAGE

The Scope of Physiology, and its Relation to the other Branches of Natural

Science, ............ xix

Matter, ............. xx

Forces, ............. xxii

Law of the Conservation of Energy, .... ... xxvii

Animals and Plants, ...... . xxviii

Vital Energy and Life, ...... ... xxxi

I. PHYSIOLOGY OF THE BLOOD.

SECTION

1. Physical Properties of the Blood, ........ 1

2. Microscopic Examination of the Blood, ....... 3

3. Histology of the Human Red Blood-Corpuscles, ..... 7

4. Effects of Reagents on the Blood-Corpuscles, ..... 7

5. Preparation of the Stroma Making Blood "Lake-Coloured," . . 10

6. Form and Size of the Blood-Corpuscles of Different Animals, . . 11

7. Origin of the Red Blood-Corpuscles, . . . . . . . 12

8. Decay of the Red Blood-Corpuscles, . . . . . . . 16

9. The Colourless Corpuscles Leucocytes, . . . . . . 17

10. Abnormal Changes of the Blood-Corpuscles, ...... 22

11. Chemical Constituents of the Red Blood-Corpxiscles, .... '_'.'{

12. Preparation of Haemoglobin Crystals, ....... 24

13. Quantitative Estimation of Haemoglobin, ...... 25

14. Use of the Spectroscope, ......... 27

15. Compounds of Haemoglobin Methseinoglobin, ..... 29

16. Carbonic Oxide-Haemoglobin, . . . . . . . . 31

17. Poisoning by Carbonic Oxide, ........ 32

18. Decomposition of Haemoglobin, ........ 33

19. Hsemin and Blood Tests, 34

20. Hsematoidin, ........... 35

21. The Colourless Proteid of Haemoglobin, 36

22. Proteids of the Stroma, ... ... .36

23. The other Constituents of Red Blood-Corpuscles, .... 36

24. Chemical Composition of the Colourless Corpuscles, .... 37

25. Blood-Plasma, and its Relation to Serum, ...... 37

26. Preparation of Plasma, ......... 38

27. Fibrin Coagulation of the Blood, ....... 39

28. General Phenomena of Coagulation, ....... 40

29. Cause of the Coagulation of the Blood, ....... 43

30. Source of the Fibrin- Factors, ........ 46

31. Relation of the Red Blood-Corpuscles to the Formation of Fibrin, . 47

X CONTENTS.

SECTION PAGE

32. Chemical Composition of the Plasma and Serum, .... 49

33. The Gases of the Blood, 51

34. Extraction of the Blood Gases, ........ 53

35. Quantitative Estimation of the Blood Gases, 55

36. The Blood Gases, ........... 55

37. Is ozone (0 3 ) present in Blood ? . . 57

38. Carbonic Acid and Nitrogen in Blood, ....... 58

39. Arterial and Venous Blood, ......... 59

40. Quantity of Blood, . . . ... 60

41. Variations from the Normal Conditions of the Blood, .... 61

II. PHYSIOLOGY OF THE CIRCULATION.

42. General View of the Circulation, 65

43. The Heart, 66

44. Arrangement of the Cardiac Muscular Fibres, ..... 67

45. Arrangement of the Ventricular Fibres, ...... 69

46. Pericardium, Endocardium, Valves, 71

47. Self-Steering Action of the Heart, 73

48. The Movements of the Heart, 76

49. Pathological Disturbances of Cardiac Action, ..... 79

50. The Apex-Beat the Cardiogram, ....... SO

51. The Time occupied by the Cardiac Movements, ..... 85

52. Pathological Disturbance of the Cardiac Impulse, .... 89

53. The Heart-Sounds. 91

54. Variations of the Heart-Sounds, 95

55. The Duration of the Movements of the Heart, 96

56. Innervation of the Heart, 97

57. The Cardiac Nerves, ... 97

58. The Automatic Motor-Centres of the Heart, ...... 98

59. The Cardio-Pneumatic Movements, ....... 109

00. Influence of the Kespiratory Pressure on the Heart, . . . .111

THE CIRCULATION.

61. The Flow of Fluids through Tubes, 115

62. Propelling Force, Velocity of Current, Lateral Pressure, . . .115

63. Currents through Capillary Tubes, US

64. Movements of Fluids and Wave-Motion in Elastic Tubes, . . .118

65. Structure and Properties of the Blood- Vessels, 119

66. The Pulse Historical, 127

67. Instruments for Investigating the Pulse, 128

68. The Pulse-Curve or Sphygmogram, 136

69. Dicrotic Pulse, 140

70. Characters of the Pulse, 141

71. Variations in the Strength, Tension, and Volume of the Pulse, . . 143

72. The Pulse-Curves of various Arteries, 144

73. Anacrotism, 146

74. Influence of the Respiratory Movements on the Pulse-Curve, . . 148

75. Influence of Pressure upon the Form of the Pulse-Wave, . . . 151

76. Rapidity of Transmission of Pulse- Waves, 152

77. Propagation of the Pulse-Wave in Elastic Tubes, .... 152

78. Velocity of the Pulse-Wave in Man, , 154

CONTENTS, XI

SECTION" PAGE

79. Further Pulsatile Phenomena ,156

80. Vibrations Communicated to the Body by the Action of the Heart, , 157

81. The Blood-Current, 159

82. Schemata of the Circulation, 161

83. Capacity of the Ventricles, ... . 161

84. Estimation of the Blood-Pressure, 162

85. Blood-Pressure in the Arteries, . .166

86. Blood-Pressure in the Capillaries, . . 173

87. Blood-Pressure in the Veins, . . . 175

88. Blood-Pressure in the Pulmonary Artery, . . ... 177

89. Measurement of the Velocity of the Blood-Stream, .... 179

90. Velocity of the Blood in Arteries, Capillaries, and Veins, . . . 182

91. Estimation of the Capacity of the Ventricles, . . . 184

92. The Duration of the Circulation, 184

93. Work of the Heart, 185

94. Blood-Current in the Smallest Vessels, ...... 186

95. Passage of the Blood-Corpuscles out of the Vessels [Diapedesis], . 189

96. Movement of the Blood in the Veins, 190

97. Sounds or Bruits within Arteries, 192

98. Venous Murmurs, 193

99. The Venous Pulse Phlebogram, . ... 194

100. Distribution of the Blood, 196

101. Plethysmography, ... 197

102. Transfusion of Blood, ... 199

THE BLOOD-GLANDS.

103. The Spleen Thymus Thyroid Supra-Renal Capsules Hypophysis

Cerebri Coccygeal and Carotid Glands, ..... 203

104. Comparative, 215

105. Historical Retrospect, 215

III. PHYSIOLOGY OF RESPIRATION.

106. Structure of the Air-Passages and Lungs, , 217

107. Mechanism of Respiration, 226

108. Quantity of Gases Respired, 227

109. Number 'of Respirations, ......... 229

110. Time occupied by the Respiratory Movements, ..... 229

111. Pathological Variations of the Respiratory Movements, . . . 233

112. General View of the Respiratory Muscles, 234

113. Action of the Individual Respiratory Muscles, 235

114. Relative Size of the Chest, 240

115. Pathological Variations of the Percussion Sounds, .... 244

116. The Normal Respiratory Sounds, 245

117. Pathological Respiratory Sounds, 245

118. Pressure in the Air-Passages during Respiration, .... 247

119. Appendix to Respiration, ......... 248

120. Peculiarly Modified Respiratory Sounds, ...... 248

121. Quantitative Estimation of C0 2 , O, and Watery Vapour, . . . 250

122. Methods of Investigation, 250

123. Composition and Properties of Atmospheric Air, 254

Xii CONTENTS.

SECTION ''AGE

124. Composition of Expired Air, . . . 254

125. Daily Quantity of Cases Exchanged, 256

126. Review of the Daily Gaseous Income and Expenditure, . . . 256

127. Conditions Influencing the Gaseous Exchanges, 256

128. Diffusion of Gases within the Lungs, ... . . 259

129. Exchange of Gases between the Blood and the Air, .... 260

130. Dissociation of Gases, 263

131. Cutaneous Respiration, ......... 264

132. Internal Respiration, . 265

133. Respiration in a Closed Space, ........ 267

134. Dyspnrea and Asphyxia, 268

135. Respiration of Foreign Gases, ........ 271

136. Accidental Impurities of the Air, . ...... 272

137. Ventilation of Rooms, .... .272

138. Formation of Mucus, 273

139. Action of the Atmospheric Pressure, 275

140. Comparative and Historical, . . 277

IV. PHYSIOLOGY OF DIGESTION.

141. The Mouth and its Glands, 279

142. The Salivary Glands, . 280

143. Histological Changes in the Salivary Glands, ..... 283

144. The Nerves of the Salivary Glands, 285

145. Action of Nerves on the Salivary Secretion, ..... 286

146. The Saliva of the Individual Glands, 291

147. The Mixed Saliva in the Mouth, 292

148. Physiological Action of Saliva, ........ '294

149. Tests for Sugar, 297

150. Quantitative Estimation of Sugar, 298

151. Mechanism of the Digestive Apparatus, ...... 298

152. Introduction of the Food, 298

153. The Movements of Mastication, 299

154. Structure and Development of the Teeth, ...... 300

155. Movements of the Tongue, ......... 304

156. Deglutition, 305

157. Movements of the Stomach, ........ 309

158. Vomiting, 310

159. Movements of the Intestine, . . . . . . .312

160. Excretion of Faecal Matter, 313

161. Influence of Nerves on the Intestine, 316

162. Structure of the Stomach, 321

163. The Gastric Juice, 325

164. Secretion of Gastric Juice, 326

165. Methods of obtaining Gastric Juice, ....... 330

166. Process of Gastric Digestion, ........ 331

167. Gases in the Stomach, 336

168. Structure of the Pancreas, 337

169. The Pancreatic Juice, 339

170. Digestive Action of the Pancreatic Juice, ...... 340

171. The Secretion of the Pancreatic Juice, ....... 340

172. Preparation of Peptonised Food, ..,,.... 345

CONTENTS. Xlii

SECTION PAGE

173. Structure of the Liver, 346

174. Chemical Composition of the Liver-Cells, 350

175. Diabetes Mellitus, or Glycosuria, ... . . 352

176. The Functions of the Liver, ... 354

177. Constituents of the Bile, ... 354

178. Secretion of Bile, 359

179. Excretion of Bile, ...... ... 361

180. Reabsorption of Bile, . .... .362

181. Functions of the Bile, . . 365

182. Fate of the Bile in the Intestine, 367

183. The IntestinalJuice, 368

184. Fermentation Processes in the Intestine, ...... 371

185. Processes in the Large Intestine, ... .... 377

186. Pathological Variations, .... . . 380

187. Comparative Physiology, ......... 383

188. Historical Retrospect, . 384

V. PHYSIOLOGY OF ABSORPTION.

189. The Organs of Absorption, , . ... 386

190. Structure of the Small and Large Intestines, 386

191. Absorption of the Digested Food, . . . .392

192. Absorptive Activity of the Wall of the Intestine, .... 395

193. Influence of the Nervous System, ....... 400

194. Feeding with "Nutrient Euemata," 400

195. Chyle-Vessels and Lymphatics, ........ 401

196. Origin of the Lymphatics, ......... 402

197. The Lymph-Glands, ; . 406

198. Properties of Chyle and Lymph, . 409

199. Quantity of Lymph and Chyle, . 412

200. Origin of Lymph, . ... 413

201. Movement of Chyle and Lymph, ....... 415

202. Absorption of Parenchymatous Effusions, ...... 418

203. Congestion of Lymph, Serous Effusions and (Edema, .... 419

204. Comparative Physiology, ....... . 420

205. Historical Retrospect, ... . ... 421

VI. PHYSIOLOGY OF ANIMAL HEAT.

206. Sources of Heat, 422

207. Homoiothermal and Poikilothertnal Animals, 426

208. Methods of Estimating Temperature Thermometiy, .... 427

209. Temperature Topography, ........ 430

210. Conditions Influencing the Temperature of Organs, .... 432

211. Estimation of the Amount of Heat Calorimetry, .... 434

212. Thermal Conductivity of Animal Tissues, ...... 436

213. Variations of the Mean Temperature, . ..... 437

214. Regulation of the Temperature, . . ..... 441

215. Income and Expenditure of Heat, ....... 445

216. Variations in Heat Production, ........ 447

217. Relation of Heat Production to Bodily Work, 447

218. Accommodation for Different Temperatures, 448

XiV CONTENTS.

SECTION PAGE

219. Storage of Heat in the Body, . 450

220. Fever, .... . .... 450

221. Artificial Increase of the Temperature, . ... 452

222. Employment of Heat, ... . 453

223. Increase of Temperature post mortem, . . . . 453

224. Action of Cold on the Body, . . 454

225. Artificial Lowering of Temperatui'e, ... . 455

226. Employment of Cold, ... 456

227. Heat of Inflamed Parts, ... . .457

228. Historical and Comparative, 457

VII. PHYSIOLOGY OF THE METABOLIC PHENOMENA

OF THE BODY.

229. General View of Food-Stuffs, . .458

230. Structure' and Secretion of the Mammary Glands, . . 461

231. Milk and its Preparations, ... . 464

232. Eggs, . 468

233. riesh and its Preparations, . ... 469

234. Vegetable Foods, . . . ... 471

235. Condiments Tea and Alcohol, 473

PHENOMENA AND LAWS OF METABOLISM.

236. Equilibrium of the Metabolism, . 476

237. Metabolism during Hunger and Starvation, . . . 482

238. Metabolism during a purely Flesh Diet, ...... 485

239. A Diet of Fat or of Carbohydrates, . .... 486

240. Mixture of Flesh and Fat, . .... 486

241. Origin of Fat in the Body, . . 487

242. Corpulence, .... . . . 488

243. The Metabolism of the Tissues, . . 490

244. Regeneration of the Tissues, ........ 493

245. Transplantation of the Tissues, ........ 497

246. Increase in Size and Weight during Growth, ..... 497

GENERAL VIEW OF THE CHEMICAL CONSTITUENTS OF

THE ORGANISM.

247. Inorganic Constituents, . 499

248. Organic Constituents Proteids, . . ..... 500

249. The Animal and Vegetable Proteids and their Properties, . . . 502

250. The Albuminoids, . . . 504

251. The Fats, . . . 508

252. The Carbohydrates, . 511

253. Historical Retrospect. . . ... . 514

LIST OF ILLUSTKATIONS.

FIGURE PAGE

1. Human coloured blood-corpuscles, .....

2. Malassez's apparatus for estimating the number of blood-corpuscle.s, . 4
*3. Gower's htemacytometer (Hawksley), .... 6

4. Eed blood-corpuscles showing various changes of shape,

5. Vaso-formative cells, .....

6. White blood-corpuscles, .... 18

7. Blood-plates and their derivatives, ....

8. Hreinoglobin crystals, ......

*9. Gower's haemoglobinometer (Hawksley), .... 26

10. Scheme of a spectroscope, ...... 28

11. Various spectra of haemoglobin, ..... 29

12. Hremin crystals, ........ 34

13. Haemin crystals prepared from traces of blood, ... 34

14. Haematoidin crystals, ....... 35

15. Scheme of Pfltiger's gas-pump, ...... 53

16. Scheme of the circulation, ...... 65

17. Muscular fibres from the heart, ..... 66

18. Muscular fibres in the left auricle, ... .68

19. Muscular fibres in the ventricles, ..... 70
*20. Lymphatic from the pericardium (Cadiat\ . . . . 71
*21. Section of the endocardium (Cadiat), . . . . .71
*22. Purkinje's fibres (Ranvier), .... 73

23. Cast of the ventricles of the human heart, .... 77

24. The closed semilunar valves, ...... 78

*25. Various cardiographs (Hermann), ..... 81

25a. Curves of the apex-beat, ...... 82

26. Changes of the heart during systole, ... 83

27. Curves from a rabbit's ventricle, ..... 86
*28. Marey's registering tambour (Hermann), .... 87

29. Curves obtained with a cardiac sound, .... 88

30. Curves from the cardiac impulse, ..... 90

31. Position of the heart in the chest (Luschka and Gairdner). . . 93
31a. Bipolar nerve-cells from a frog's heart, . . . .98

*32. Scheme of a frog-manometer (Stirling), ..... 102

*32a. Perfusion cannula (Kronecker and Stirling), , 102

*33. Roy's tonometer (Stirling), ... .103

*34. Luciani's groups of cardiac pulsations (Hermann), , . , 104

*35. Curves of a frog's heart at different temperatures (Hermann), . , J05

36. Cardio-pneumograph of Landois, , , , .110

xvi ILLUSTRATIONS.

FIGUKE PAGE

37. Apparatus for showing the effect of respiration, . . .113

38. Cylindrical vessel, . . . . . . .115

39. Cylindrical vessel with manometers, ..... 116

40. Small artery with its various coats, . . . . .120

41. Capillaries injected with silver nitrate, . . . 122
*42. Longitudinal section of a vein at a valve (Cadiat), . . . 123

43. Poiseuille's pulse-measurer, ...... 128

44. Sphyguiometer of Herisson, . . . . 128

45. Scheme of Marey's sphj'gmogi-aph, . . . . .129
*46. Marey's improved sphygmograph (B. Bramwell), . . . 130
*47. Scheme of Marey's sphygmograph in working order (B. Bramwell), . 130
*48. Scheme of Marey's sphygmograph after increase of the pressure (B.

Bramwell), ... 130

*49. Dudgeon's sphygmograph (Dudgeon), . . . . 131

*50. Mode of applying Dudgeon's sphygmograph (Dudgeon), . . 131

*51. Sphygmogram (Dudgeon), ...... 132

52. Scheme of Brondgeest's pansphygmograph, .... 132

53. Scheme of Landois' angiograph, . . . . .133

54. Pulse-curves of the carotid, radial, and posterior tibial arteries, . 134

55. Landois' gas-sphygraoscope, ...... 135

56. Hremautographic curve, . . . . . . .136

*57. Sphygmogram of radial artery (Dudgeon), .... 137

58. Sphygmograms of various arteries, ..... 138

59. Pulsus dicrotus, P. caprizans, P. monocrotus. . . . .140

60. Pulsus alteruans, ....... 143

61. Curves of the posterior tibial and pedal arteries, . . 145

62. Anacrotic pulse-curves, ....... 147

63. Influence of the respiration on the Sphygmogram, . . 148

64. Curves of the radial and carotid arteries during Miiller's and Val-

salva's experiments, .... 150

65. Pulsus paradoxus, ..... 150

66. Various radial cui-ves altered by pressure, .... 151

67. Apparatus for measuring the velocity of the pulse-wave in an elastic

tube, ....... 153

67. Tracing obtained from 67, .... 154

68. Pulse tracings of the radial and carotid arteries, . . 155

69. Tracings from the posterior, tibial, and carotid arteries, 156

70. Apparatus for registering the molar motions of the body, 157

71. Vibration and heart ciirves, , 158

72. Ludwig and Fick's kymographs, . . 163
*73. Ludwig's improved revolving cylinder (Hermann), . . 164
*74. Blood-pressure tracing of the carotid of a dog (Hermann), . . 165
*75. Fick's spring kymograph by Heriug (Hermann), . . 166
*76. Depressor curve (Stirling), ...... 168

77. Blood-pressure and respiration tracings taken simultaneously, . 169

78. Blood-pressure tracing during stimulation of the vagus (Stirling), . 173

79. f Apparatus of v. Kries for estimating the capillary pressure (C. "),-,
SO. \ Ludwig), ...... j

81. Volkmann's htemadromometer, ..... ISO

82. Ludwig and Dogiel's rheometer, .... ISO
S3. Vierordt's hrcmataehometer, .... . 181
84. Dromograph, . . . . . . . .182

*

ILLUSTRATIONS. XVil

PAGE

85. Diapedesis, . . . ; . . . .190

86. Various forms of venous pulse, ..... 195

87. Mosso's plethysmograph, ...... 198

*88. Trabeculaa of the spleen (Cadiat), 203

*S9. Adenoid tissue of spleen (Cadiat), ..... 203

*90. Malpighian corpuscle of the spleen (Cadiat), .... 205

*91. Tracing of a splenic curve (Roy), ..... 209

*92. Thymus gland (Cadiat), ....... 212

*93. Elements of the thymus gland (Cadiat), . . . .212

*94. Thyroid gland (Cadiat), 213

*95. Supra-renal capsule (Cadiat), ...... 214

*97. Human bronchus (Hamilton), ...... 219

*98. Air-vesicles injected with silver nitrate (Hamilton), . . 221

99. Scheme of the air- vesicles of lung, ..... 222
*100. Interlobular septa of lung (Hamilton), . . . .223

101. Scheme of Hutchinson's spirometer,' ..... 228

102. Marey's stethograph (M'Kendrick), ..... 230

103. Brondgeest's tambour and curve, ..... 230

104. Pneumatogram, ....... 231

105. Section through diaphragm (Hermann), .... 236

106. Action of intercostal muscles, ...... 237

107. Cyrtometer curve, ....... 241

108. Sibson's thoracometer, ....... 242

109. Topography of the lungs and heart, ..... 243

110. Andral and Gavarret's respiration apparatus, . . . 251

111. Scharling's apparatus, . . . . . . .251

112. Regnault and Reiset's apparatus, ..... 252

113. v. Pettenkofer's apparatus, ...... 253

114. Valentin and Bruuner's apparatus, ..... 255

115. Objects found in sputum, ...... 274

116. Histology of the salivary glands, ..... 281
*117. Human sub-maxillary gland (Heidenhain), .... 282

*118 )

*119 ( Sections of a serous gland (Heidenhain), . 284

*120. Diagram of a salivary gland (L. Brunton), . . . 289

121. Apparatus for estimation of sugar, ..... 298

122. Vertical section of a tooth, ...... 300

123. Dentine, ........ 300

124. Dentine and enamel, ....... 301

125. Dentine and crusta petrosa, .'.... 302

126. )

127. [Development of a tooth, . 302 and 303

128. )

129. Perinaeum and its muscles, ...... 314

130. Levator ani externus and internus, ..... 315

131. Auerbach's plexus (Cadiat), ...... 317

132. Meissner's plexus (Cadiat), ... . . 317

133. Surface section of gastric mucous membrane, .... 321

134. Fundus gland of the stomach, ...... 322

135. Pyloric gland and goblet-cells, ...... 323

136. Scheme of the gastric mucous membrane, .... 324

137. Pyloric mucous membrane (Hermann), .... 326

*

xviii ILLUSTRATIONS.

FIGURE PAGE

*13S. Pyloric glands during digestion (Hermann), .... 326

*139. Section of the tubes of the pancreas (Hermann), . . . 337

140. Changes of the pancreatic cells during activity, . . 338

141. Scheme of a liver lobule, . . % 347
*142. Human liver-cells (Cadiat), ...... 348

*143. Liver-cells during fasting (Hermann), ..... 348

144. Various appearances of the liver-cells, . 349

*145. Cholesterin (Aitken), ...... 358

*146. Lieberkuhn's gland (Hermann), . . 369

147. Bacterium aceti and B. butyricus, ... 373

148. Bacillus subtilis, . . . . . .375
*149. Villi of small intestine injected (Cadiat), . . 387

150. Scheme of an intestinal villus, . . 388

*151. Villi and Lieberkiihn's follicles (Cadiat), 389

*152. Section of a solitary follicle (Cadiat), .... 390

*153. Section of a Peyer's patch (Cadiat), ..... 391

*154. Section of Auerbach's plexus (Cadiat), .... 391

*155. Lieberkiihn's gland (Hermann), . . . 392

156. Endosmometer, ....... 393

157. Origin of lymphatics in the tendon of diaphragm, . . . 403
*158. Lymphatics of diaphragm silvered (Ranvier), . . . 403

159. Perivascular lymphatics, ... ... 405

160. Stomata from lymph-sac of frog, ..... 405

161. Section of two lymph-follicles, ..... 406
*162. Scheme of a lymphatic gland (Knott), .... 407

163. Part of a lymphatic gland ...... 408

*164. Section of central tendon of diaphragm (Brunton), . . . 416

*165. Section of fascia lata of a dog (Brunton), .... 416

166. Water calorimeter of Favre and Silbermann, .... 422

167. Walferdin's metastatic thermometer, ..... 427

168. Scheme of thermo-electric arrangements, .... 428

169. Kopp's apparatus for specific heat, . . . . . . 435

170. Daily variations of temperature, ..... 439
*171. Acini of the mammary gland of a sheep (Cadiat), . . . 462

172. Milk-glands during inaction and secretion, .... 462

*173. Section of a grain of wheat (Blyth), ..... 471

174. Yeast-cells growing, ....... 474

175. Composition of animal and vegetable foods, .... 479

176. Starch grains (Blyth), . . . . . 512

[The illustrations indicated by the word Hermann, are from Hermann's
Handbuch der Physiologie; by Cadiat, from Cadiat's Traite d'Anatomie Gen&rale;
by Ranvier, from Ranvier's Traite Technique d 'Histologie ; by Brunton, from The.
Practitioner; and by Hamilton, from, Hamilton's Pathology of Bronchitis.]

Introduction,

The Scope of Physiology and its Eelations to other
Branches of Natural Science,

PHYSIOLOGY is the science of the vital phenomena of organisms, or
broadly, it is the Doctrine of Life. Correspondingly to the divisions
of organisms, we distinguish (1) Animal Physiology; (2) Vegetable
Physiology ; and (3) the Physiology of the Lowest Living Organisms, which
stand on the border line of animals and plants ie., the so-called
Protistce of Hseckel, micro-organisms, and those elementary organisms
or cells which exist on the same level.

The object of Physiology is to establish these phenomena, to deter-
mine their regularity and causes, and to refer them to the general
fundamental laws of Natural Science, viz., the Laws of Physics and of
Chemistry.

The following Scheme shows the relation of Physiology to the
allied branches of Natural Science :

Biology.

The science of organised beings or organisms (animals, plants,
protistae, and elementary organisms).

I. Morphology.

The doctrine of the form of

organisms.

General
Morphology.

The doctrine of the
formed elemen-
tary constituents
of organisms.

(Histology)

(a) Histology of

Plants,
(6) Histology of

Animals.

Special
Morphology.
The doctrine of
the parts and
organs of organ-
isms.

(Organology
Anatomy)
(a) Phytotomy,
(6) Zootomy.

II. Physiology-

The doctrine of the vital pheno-
mena of organisms.

General
Physiology.

The doctrine of
vital phenomena
in general
(a) Of Plants,
(6) Of Animals.

Special
Physiology.

The doctrine of
the activities of
the individual
organs
(a) Of Plants,
(6) Of Animals.

XX

INTRODUCTION.

Morphological part of the
doctrine of develop-
ment, i.e., the doctrine
of form in its stages of
development

(a) Genera],

(b) Special.

Physiological part of the
doctrine of develop-
ment, i.e., the doctrine
of the activity during
development

(a) General,

(b) Special.

III. Embryology.

The doctrine of the generation and development of organisms.

ML History of the develop-
ment of single beings,
of the individual (.e.g. ,
of man) from the ovum

onwards (Ontogeny) :

(a) In Plants,

(b) In Animals.

2. History of the develop-
ment of a whole stock
of organisms from the
lowest forms of the
series upwards Phy-

logeny)

(a) In Plants,

(b) In Animals.

v_ --

Morphology and Physiology are of equal rank in biological science,
and a previous acquaintance with Morphology is assumed as a basis
for the comprehension of Physiology, since the work of an organ
can only be properly understood when its external form and its
internal arrangements are known. Development occupies a middle
place between Morphology and Physiology; it is a morphological
discipline in so far as it is concerned with the description of the parts
of the developing organism ; it is a physiological doctrine in so far
as it studies the activities and vital phenomena during the course of
development.

Matter,

The entire visible world, including all organisms, consists of
matter, i.e., of substance which occupies space.

We distinguish ponderable matter which has weight, and imponderable
matter which cannot be weighed in a balance. The latter is generally
termed ether.

In ponderable materials, again, we distinguish their form, i.e., the
nature of their limiting surfaces ; further, their volume, i.e., the
amount of space which they occupy; and lastly, their aggregate condition,
i.e., whether they are solid, fluid, or gaseous bodies.

Ether. The ether fills the space of the universe, certainly as far
as the most distant visible stars. This ether, notwithstanding its
imponderability, possesses distinct mechanical properties ; it is infinitely
more attenuated than any known kind of gas, and behaves more like

INTRODUCTION. XXI

a solid body than a gas, resembling a gelatinous mass rather than the
air. It participates in the luminous phenomena due to the vibrations
of the atoms of the fixed stars, and hence it is the transmitter of
light, which is conducted by means of its vibrations, with inconceivable
rapidity (42,220 geographical miles per sec.) to our visual organs
(Tyndall).

Imponderable matter (ether) and ponderable matter are not
separated sharply from each other; rather does the ether penetrate
into all the spaces existing between the smallest particles of ponderable
matter.

Particles. Supposing that ponderable matter were to be sub-
divided continuously into smaller and smaller portions, until we
reached the last stage of division in which it is possible to recognise
the aggregate, condition of the matter operated upon, we should call
the finely-divided portions of matter in this state particles. Particles
of iron would still be recognised as solid, particles of water as fluid,
particles of oxygen as gaseous.

Molecules. Supposing, however, the process of division of the
particles to be carried further still, we should at last reach a limit
beyond which, neither by mechanical nor by physical means, could
any further division be effected. We should have arrived at the
molecules. A molecule, therefore, is the smallest amount of matter
which can still exist in a free condition, and which as a unit no
longer exhibits the aggregate condition.

Atoms. But even molecules are not the final units of matter, since
every molecule consists of a group of smaller units, called atoms. An
atom cannot exist by itself in a free condition, but the atoms unite
with other similar or dissimilar atoms to form groups, which are
called molecules. Atoms are incapable of further sub-division, hence
their name. We assume that the atoms are invariably of the same
size, and that they are solid. From a chemical point of view, the
atom of an elementary body (element) is the smallest amount of
the element which can enter into a chemical combination. Just as
ponderable matter consists in its ultimate parts of ponderable atoms,
so does the ether consist of analogous small ether-atoms.

Ponderable and Imponderable Atoms. The ponderable atoms within
ponderable matter are arranged in a definite relation to the ether-
atoms. The ponderable atoms mutually attract each other, and
similarly, they attract the imponderable ether-atoms; but the ether-
atoms repel each other. Hence, in ponderable masses, ether-atoms
surround every ponderable atom. These masses, in virtue of the
attraction of the ponderable atoms, tend to come together, but only

XX11 INTRODUCTION.

to the extent permitted by the surrounding ether-atoms. Thus, the
ponderable atoms can never come so close as not to leave interspaces.
All matter must, therefore, be regarded as more or less loose and
open in texture, a condition due to the interpenetrating ether-atoms,
which resist the direct contact of the ponderable atoms.

Aggregate Condition of Atoms. The relative arrangement of the
molecules, i.e., the smallest particles of matter, which can be isolated in
a free condition, determines the aggregate condition of the body.

Within a solid body, characterised by the permanence of its volume,
as well as by the independence of its form, the molecules are so
arranged that they cannot readily be displaced from their relative
positions.

Fluid bodies, although their volume is permanent, readily change
their shape, and their molecules are in a condition of continual
movement.

When this movement of the molecules takes so wide a range that
the individual molecules fly apart, the body becomes gaseous, and as
such, is characterised by the instability of its form as well as by the
changeableness of its volume.

Physics is the study of these molecules and their motions.

Forces.

1. Gravitation Work done.

All phenomena appertain to matter. These phenomena are the
appreciable expression of the forces inherent in matter. The forces
themselves are not appreciable, they are the causes of the phenomena.

1 . Gravitation. The law of gravitation postulates that every particle
of ponderable matter in the universe, attracts every other particle with
a certain force. This force is inversely as the square of the distance.
Further, the attractive force is directly proportional to the amount of
the attracting matter, without any reference to the quality of the body.
We may estimate the intensity of gravitation, by the extent of the
movement which it communicates to a body allowed to fall, for one
second, through a given distance, in a space free from air. Such a body
will fall in vacuo 9 '809 metres per second. This fact has been arrived
at experimentally.

Let us represent g = 9 '809 metres, the final velocity of the freely falling body at
the end of one second. The velocity, V, of the freely falling body is proportional
to the time, t, so that

V = 9t (1);

.INTRODUCTION. xxill

i.e., at the end of the 1st sec., V = g, 1 = g = 9'809M the distance traversed

s = f 2 (2);

i.e., the distances are as the square of the times. Hence, from (1) and (2) it follows
(by eliminating t) that

V= V2<7 ......... (3).

The velocities are as the square roots of the distances traversed

V 2
Therefore, ~~= s ........... (4).

The freely falling body, and in fact every freely moving body, possesses
kinetic energy, and is in a certain sense a magazine of energy. The
kinetic energy of any moving body is always equal to the product of
its weight (estimated by the balance), and the height to which it
would rise from the earth, if it were thrown from the earth with its
own velocity.

Let W represent the kinetic energy of the moving body, and P its weight, then
W = P. s, so that from (4) it follows that

Hence, the kinetic energy of a body is proportional to the square of
its velocity.

Work. If a force (pressure, strain, tension) be so applied to a body
as to move it, a certain amount of work is performed. The amount of
work is equal to the product of the amount of the pressure or strain
which moves the body, and of the distance through which it is moved.

Let K represent the force acting on the body, and S the distance, then the
work W = K S. The attraction between the earth and any body raised above it
is a source of work.

It is usual to express the value of K in kilogrammes, and S in
metres, so that the " unit of work" is the kilogramme-metre, i.e., the force
which is required to raise 1 kilo, to the height of 1 metre.

2. Potential Energy. The transformation of Potential into Kinetic
energy, and conversely : Besides kinetic energy, there is also " potential
energy," or energy of position. By this term are meant various forms
of energy, which are suspended in their action, and which, although
they may cause motion, are not in themselves motion. A coiled watch-
spring kept in this position, a stone resting upon a tower, are instances
of bodies possessing potential energy, or the energy of position. It
requires merely a push to develop kinetic from the potential energy,
or to transform potential into kinetic energy.

XXIV INTRODUCTION.

Work, w, was performed in raising the stone to rest upon the
tower.

iu=.p, s, where p = ihe weight and ,s = the height,
p = m . g, is = the product of the mass (m), and the force of gravity (</), so that

This is at the same time the expression for the potential energy of
the stone. This potential energy may readily be transformed into
kinetic energy by merely pushing the stone so that it falls from the
tower. The kinetic energy of the stone is equal to the final velocity
with which it impinges upon the earth.

V = V "2gs (see above (3).

- = 2 my s.

m

6 - V- = m g s.

m g s was the expression for the potential energy of the stone while

9??

it was still resting on the height; - V 2 is the kinetic energy corre-

sponding to this potential energy (Briicke).

Potential energy may be transformed into mechanical energy under
the most varied conditions; it may also be transferred from one body
to another.

The movement of a pendulum is a striking example of the former. When the
pendulum is at the highest point of its excursion, it must be regarded as absolutely
at rest for an instant, and as endowed with potential energy, thus corresponding
with the raised stone in the previous instance. During the swing of the pendulum,
this potential energy is changed into kinetic energy, which is greatest when the
pendulum is moving most rapidly towards the vertical. As it rises again from
the vertical position, it moves more slowly, and the kinetic energy is changed
into potential energy, which once more reaches its maximum, when the pen-
dulum comes to rest at the utmost limit of its excursion. Were it not for the
resistances continually opposed to its movements, such as the resistance of the
air, and friction, the movement of the pendulum, due to the alternating change of
kinetic into potential energy and vice versa, would continue uninterruptedly, as
with a mathematical pendulum. Suppose the swinging ball of the pendulum,
when exactly in a vertical position, impinged upon a resting but movable sphere,
the potential energy of the ball of the pendulum would be transferred directly to
the sphere, provided that the elasticity of the ball of the pendulum and the sphere
were complete; the pendulum would come to rest, while the sphere would move
onward with an equal amount of kinetic energy, provided there were no resistance
to its movement. This is an example of the transference of kinetic energy from
one body to another. Lastly, suppose that a stretched watch-spring on uncoiling
causes another spring to become coiled; and we have another example of the
transference of kinetic energy from one body to another.

The following general statement is deducible from the foregoing
examples: If, in a system, the individual moving masses approach the
final position of equilibrium, then in this system the sum of the kinetic

INTRODUCTION. XXV

energies increases ; if, on the other hand, the particles move away from
the final position of equilibrium, then the sum of the potential energies
is increased at the expense of the kinetic energies, i.e., the kinetic
energies diminish (Briicke).

The pendulum, which, after swinging from the highest point of its excursion,
approaches the vertical position, i.e., the position of equilibrium of a passive pen-
dulum, has in this position the largest amount of potential energy; as it again
ascends to the highest point of its excursion on the other side, it again gradually
receives the maximum of potential energy at the expense of the gradually diminish-
ing movement, and therefore of the kinetic energy.

3. Heat Its Relation to Potential and Kinetic Energy. If a lead
weight be thrown from a high tower to the earth, and if it strike an
unyielding substance, the movement of the mass of lead is not only
arrested, but the kinetic energy (which to the eye appears to be lost),
is transformed into a lively vibratory movement of the atoms. When
the lead meets the earth, heat is produced. The amount of heat pro-
duced is proportional to the kinetic energy, which is transformed
through the concussion. At the moment when the lead weight
reaches the earth, the atoms are thrown into vibrations ; they impinge
upon each other ; then rebound again from each other in consequence
of their elasticity, which opposes their direct juxtaposition ; they fly
asunder to the maximum extent permitted by the attractive force of
the ponderable atoms, and thus oscillate to and fro. All the atoms
vibrate like a pendulum, until their movement is communicated to the
ethereal atoms surrounding them on every side, i.e., until the heat of
the heated mass is " radiated" Heat is thus a vibratory movement of the
atoms.

As the amount of heat produced is proportional to the kinetic energy,
which is transformed through the concussion, we must find an adequate
measure for both forces.

Heat-Unit. As a standard of measure of heat, we have the "heat-
unit" or calorie. The "heat-unit" or calorie is the amount of energy
required to raise the temperature of 1 gramme of water 1 centigrade.
The "heat-unit" corresponds to 425*5 gramme-metres, i.e., the same
energy required to heat 1 gramme of water 1C. would raise a weight of
425'5 grammes to the height of 1 metre; or, a weight of 425'5 grammes,
if allowed to fall from the height of 1 metre, would by its concussion,
produce as much heat as would raise the temperature of 1 gramme of
water 1C. The "mechanical equivalent'' of the heat-unit is, there-
fore, 425'5 gramme-metres.

It is evident, that from the collision of moving masses, an immeasurable amount
of heat can be produced. Let us apply what has already been said to the earth.
Suppose the earth to be disturbed in its orbit, and suppose further that, owing to

xxvi INTRODUCTION.

the attraction of the sun, it were to impinge on the latter (whereby, according
to J. R. Mayer, its final velocity would be 85 geographical miles per second), the
amount of heat produced by the collision would be equal to that produced by the
combustion of a mass of pure charcoal more than 5000 times as heavy (Julius
Eobert Mayer, Helmholtz).

Thus, the heat of the sun itself can be produced by the collision of masses of cold
matter. If the cold matter of the universe were thrown into space, and there
left to the attraction of its particles, the collision of these particles would ulti-
mately produce the light of the stars. At the present time, numerous cosmic bodies
collide in space, while innumerable small meteors (94,000-188,000 billions of kilos,
per minute) fall into the sun. The force of gravity is perhaps, in fact, the only
source of all heat (J. R. Mayer, Tyndall).

We have a homely example of the transformation of kinetic energy into heat in
the fact, that a blacksmith may make a piece of iron red-hot by hammering it. Of
the conversion of heat into kinetic energy, we have an example in the hot watery
vapour (steam) of the steam-engine raising the piston. An example of the conver-
sion of potential energy into heat occurs, in a metallic spring, when it uncoils and
is so placed as to rub against a rough surface, producing heat by friction.

4. Chemical Affinity : Eolation to Heat. Whilst gravity acts upon
the particles of matter without reference to the composition of the
body, there is another atomic force which acts between atoms of a
chemically different nature ; this is chemical affinity. This is the force,
in virtue of which the atoms of chemically-different bodies unite to
form a chemical compound. The force itself varies greatly between the
atoms of different chemical bodies ; thus, we speak of strong chemical
affinities and weak affinities. Just as we were able to estimate the
potential energy of a body in motion, from the amount of heat which
was produced when it collided with an unyielding body, so we can
measure the amount of the chemical affinity by the amount of heat
which is formed, when the atoms of chemically-different bodies unite to
form a chemical compound. As a rule, heat is formed when separate,
chemically-different atoms, form a compound body. When in virtue
of chemical affinity, the atoms of 1 kilo, of hydrogen and 8 kilos, of
oxygen unite to form the chemical compound water, an amount of heat
is thereby evolved which is equal to that produced by a weight of
47,000 kilos, falling and colliding with the earth from a height of
1000 feet above the surface of the earth. If 1 gram, of H be burned
along with the requisite amount of O to form water, it yields 34,460
heat-units or calories; and 1 gram, carbon burned to carbonic acid
(carbon dioxide) yields 8,080 heat-units. Wherever, in chemical processes,
strong chemical affinities are satisfied, heat is set free i.e., chemical affinity
is changed into heat. Chemical affinity is a form of potential energy
obtaining between the most different atoms, which during chemical
processes is changed into heat. Conversely, in those chemical processes
where strong affinities are dissolved, and chemically-united atoms
thereby pulled asunder, there must be a diminution of temperature, or,

INTRODUCTION. XXV11

as it is said, heat becomes latent that is, the energy of the heat which
has become latent is changed into chemical energy, and this, after
decomposition of the compound chemical body, is again represented by
the chemical affinity between its isolated different atoms.

Law of the Conservation of Energy.

Julius Robert Mayer and Helmholtz have established the important
law, that in a system which does not receive any influence and impres-
sion from without, the sum of all the forces acting within it is always the
same. The various fm-ms of energy can be transformed one into the other,
so that kinetic energy may be transformed into potential energy and vice versa,
but there is never any part of the energy lost. The transformation takes
place in such measure that, from a certain definite amount of one form
of energy, a definite amount of another can be obtained.

The various forms of energy acting in organisms occur in the follow-
ing modifications :

1. Molar motion (ordinary movements), as in the movements of the
whole body, of the limbs, or of the intestines, and even those observable
microscopically in connection with cells.

2. Movements of Atoms as Heat. We know, in connection with
the vibration of atoms, that the number of vibrations in the unit of
time determines whether the oscillations appear as heat, light, or
chemically-active vibrations. Heat-vibrations have the smallest
number, while chemically-active vibrations have the largest number,
light-vibrations standing between the two. In the human body, we
only observe heat-vibrations, but some of the lower animals are capable
of exhibiting the phenomena of light.

In the human organism, the molar movements in the individual
organs are constantly being transformed into heat, e.g., the kinetic
energy in the organs of the circulation is transformed by friction into
heat. The measure of this is the "unit of u<orJc" = l gramme-metre,
and the "unit of heat" = 4:25-5 gramme-metres.

3. Potential Energy. The organism contains many chemical com-
pounds which are characterised by the great complexity of their
constitution, by the imperfect saturation of their affinities, and hence,
by their great tendency to split up into simpler bodies.

The body -can transform the potential energy into heat as well as
into kinetic energy, the latter always in conjunction with the former,
but the former always by itself alone. The simplest measure of the
potential energy is the amount of heat, which can be obtained by complete
combustion of the chemical compounds representing the potential

XXV111 INTRODUCTION.

energy. The number of work-units can then be calculated from the
amount of heat produced.

4. The phenomena of electricity, magnetism, and diamagnetism
may be recognised in two directions, as movements of the smallest
particles, which are recognised in the glowing of a thin wire when it
is traversed by strong electrical currents (against considerable resist-
ance), and also as molar movement, as in the attraction or repulsion of
the magnetic needle. Electrical phenomena are manifested in our
bodies by muscle, nerve, and glands, but these phenomena are rela-
tively small in amount when compared with the other forms of energy.
It is not improbable that the electrical phenomena of our bodies
become almost completely transformed into heat. As yet experiment
has not determined with accuracy a "unit of electricity," directly
comparable with the "heat-unit" and the "work-unit."

It is quite certain that within the organism, one form of energy can
be transformed into another form, and that a certain amount of one
form will yield a definite amount of another form; further, that new
energy never arises spontaneously, nor is energy, already present, ever
destroyed, so that in the organism the law of the conservation of
energy is continually in action.

Animals and Plants.

The animal body contains a quantity of chemically-potential energy
stored up in its constituents. The total amount of the energy present
in the human body might be measured, by burning completely an entire
human body in a calorimeter, and thereby determining how many heat-
units are produced when it is reduced to ashes (see Animal Heat,
p. 422).

The chemical compounds containing the potential energy are
characterised by the complicated relative position of their atoms, by a
comparatively imperfect saturation of the affinities of their atoms, by
the relatively small amount of oxygen which they contain, by their
great tendency to decomposition, and the facility with which they
undergo it.

If a man were not supplied with food, he would lose 50 grammes of
his body-weight every hour ; the material part of his body, which
contains the potential energy, is used up, oxygen is absorbed, and a
continual process of combustion takes place; by the process of com-
bustion, simpler substances are formed from the more complex
compounds, whereby potential is converted into kinetic energy. It is
immaterial whether the combustion is rapid or slow ; the same amount

INTRODUCTION, XXIX

of the same chemical substances always produces the same amount of
kinetic energy, i.e., of heat.

A person when fasting, experiences after a certain time, the dis-
agreeable feeling of exhaustion of his reserve of potential energy,
hunger sets in, and he takes food. All food for the animal kingdom is
obtained, either directly or indirectly, from the vegetable kingdom. Even
carnivora, which eat the flesh of other animals, only eat organised
matter which has been formed from vegetable food. The existence of
the animal kingdom presupposes the existence of the vegetable
kingdom.

All substances, therefore, necessary for the food of animals occur in
vegetables. Besides water and the inorganic constituents, plants
contain, amongst other organic compounds, the following three chief re-
presentatives of food-stuffs fats, carbohydrates, and proteids.

All these contain stores of potential energy, in virtue of their com-
plex chemical constitution.

The fats contain :- j Cn !^-< H) = f f* add9 } ( 251).

( + C 3 H 5 (OH) 3 = glycerine j

The carbohydrates contain : C 6 H 10 5 . . . ( 252).

f C. 51-5-54-5 '

H. 6-9- 7-3

The proteids contain per cent.: { N. 1 5-2-17-0

I 0. 20-9-23-5

[ S. 0-3- 2-0 J

A man, who takes a certain amount of this food adds thereto oxygen
from the air in the process of respiration. Combustion or oxidation
then takes place, whereby chemically potential energy is transformed
into heat.

It is evident, that the products of this combustion must be bodies of
simpler constitution bodies with less complex arrangement of their
atoms, with the greatest possible saturation of the affinities of their
atoms, of greater stability, partly rich^in 0, and possessing either no
potential energy, or only very little. These bodies are carbonic acid
(carbon dioxide), C0 2 ; water, H 2 0; and as the chief representative of
the nitrogenous excreta, urea (CO(NH 2 ) 2 ), which has still a small
amount of potential energy, but which outside the body readily splits
into C0 2 and ammonia (NH 3 ).

The human body is an organism in which, by the phenomena of
oxidation, the complex nutritive materials of the vegetable kingdom,
which are highly charged with potential energy, are transformed into
simple chemical bodies, whereby the potential energy is transformed

XXX INTRODUCTION.

into the equivalent amount of kinetic energy (heat, work, electrical
phenomena).

But how do plants form these complex food-stuffs so rich in potential
energy? It is plain, that the potential energy of plants must be
obtained from some other form of energy. This potential energy
is supplied to plants by the rays of the sun, whose chemical light-rays
are absorbed by plants. Without the rays of the sun there could be no
plants. Plants absorb from the air and the soil, C0 2 , H 2 0, NH 3 , and N,
of which carbonic acid, water, and ammonia (from urea), are also pro-
duced by the excreta of animals. Plants absorb the kinetic energy of
light from the suns rays and transform it into potential energy, which is
accumulated during the growth of the plant in its tissues, and in the
food-stuffs produced in them during their growth. This formation of
complex chemical compounds is accompanied by the simultaneous
excretion of 0.

Occasionally, kinetic energy, such as we universally meet with in animals, is
liberated in plants. Many plants develop considerable quantities of heat in their
flowers e.g., the arum tribe. We must also remember that, during the forma-
tion of the solid parts of plants, when fluid juices are changed into solid masses,
heat is set free. In plants, under certain circumstances, is absorbed, and C0 2
is excreted, but these processes are so trivial as compared with the typical condi-
tion in the vegetable kingdom, that they may be regarded as of small moment.

Plants, therefore, are organisms which, by a reduction process, trans-
form simple stable combinations into complex compounds, whereby
potential solar energy is transformed into the chemically-potential
energy of vegetable tissues. Animals are living beings, which, by
oxidation, decompose or break up the complex grouping of atoms
manufactured by plants, whereby potential is transformed into kinetic
energy. Thus, there is a constant circulation of matter and a constant
exchange of energy between plants and animals. All the energy of
animals is derived from plants. All the energy of plants arises from
the sun. Thus the sun is the cause, the original source of all energy
in the organism, i.e., of the whole of life.

As the formation of solar heat and solar light is explicable by the
gravitation of masses, gravity is perhaps the original form of energy of
all life.

We may thus represent the formation of kinetic energy in the animal
body from the potential energy of plants. Let us suppose the atoms of
the substances formed in organisms, as simple small bodies, balls, or
blocks. As long as these lie in a single layer, or in a few layers, upon
the surface, there is a stable arrangement, and they continue to
remain at rest. If, however, an artificial tower be built of these
blocks, so that an unstable erection is produced, and the same tower
be afterwards knocked down, then for this purpose we require (1)

INTRODUCTION. XXXI

the motor power of the workman who lifts and carries the blocks ; (2)
a blow or other impulse from without applied to the unstable structure
when the atoms will fall together, and as they fall collide with each
other and produce heat. Thus, the energy employed by the workman
is again transformed into the last-named form of energy.

In plants, the complex unstable building of the groups of atoms is
carried on, the constructor being the sun. In animals, which eat
plants, the complex groups of the atoms are tumbled down, with the
liberation of kinetic energy.

Vital Energy and Life,

The forces which act in organisms, in plants and animals are exactly
the same as are recognisable as acting in dead matter. A so-called
" vital force," as a special force of a peculiar kind, causing and governing
the vital phenomena of living beings, does not exist. The forces of all
matter, of organised as well as unorganised, exist in connection with
their smallest particles or atoms. As, however, the smallest particles of
organised matter are, for the most part, arranged in a very complicated
way, compared with the much simpler composition of inorganic bodies,
so the forces of the organism, connected with the smallest particles,
yield more complicated phenomena and combinations, whereby it is
excessively difficult to ascribe the vital phenomena in organisms to the
simple fundamental laws of physics and chemistry.

The Exchange of Material, or Metabolism (StoffwecliseT) as a Sign of
Life. Nevertheless, there appears to be a special exchange of matter
and energy peculiar to living beings. This consists in the capacity of
organisms to assimilate the matter of their surroundings, and to work
it up into their own constitution, so that it forms for a time an integral
part of the living being, to be given off again. The whole series of
phenomena is called Metabolism or Stoffwechsel, which consists in the
introduction, assimilation, integration, and excretion of matter.

We have already shown, that the metabolism of plants and that of
animals are quite different. The processes, as already described,
are actually what occur in the typical higher plants and animals.

But there is a large group of organisms which, throughout their
entire organisation, exhibit so low a degree of development, that by
some observers they are considered as undifferentiated " ground-forms."
They are regarded as neither plants nor animals, and are the most
simple forms of animated matter. Hseckel has called these organisms
Protista, as being the original and primitive forms.

We must assume that, corresponding with their simpler vital condi-
tions, their metabolism is also simpler, but on this point we still
require further observations.

Physiology of the Blood,

[THE blood is aptly described by Claude Bernard as an internal medium,
which acts as a " go-between " for the outer world and the tissues.
Into it are poured those substances which have been subjected to the
action of the digestive fluids, and in the lungs or other respiratory
organs it receives oxygen. It thus contains new substances, but in its
passage through the tissues it gives up some of these new substances,
and receives in exchange certain effete and more or less useless sub-
stances which have to be got rid of. Its composition is thus highly
complex, containing, as it does, things both new and old. It is at
once a great pabulum-supplying medium, and a channel for getting rid
of useless materials. As the composition of the organs through which
the blood flows varies, it is evident that its composition must vary
in different parts of the circulatory system ; and it also varies in the
same individual under different conditions. Htill, with slight varia-
tions, there are certain general physical, histological, and chemical
properties which characterise blood as a ivhok.~]

1. Physical Properties of the Blood.

(1.) Colour. The colour of blood varies from a bright scarlet-red
in the arteries to a deep, dark, bluish-red in the veins. Oxygen (and,
therefore, the air) makes the blood bright-red ; want of oxygen makes
it dark. Blood free from oxygen (and also venous blood) is dichroic
I.e., by reflected light it appears dark-red, while by transmitted
light it is green (Briicke).

In thin layers blood is opaqiie, as is easily shown by shaking blood
so as to form bubbles, or by allowing blood to fall upon a plate with
a pattern on it, and pouring it off again. Blood behaves, therefore,
like an " opaque colour " (Kollett), as its colouring-matter is suspended
in the form of fine particles the blood-corpuscles.

Hence, it is possible to separate the colouring-matter from the fluid part of the
blood by nitration. This is accomplished by mixing the blood with fluids which
render the blood-corpuscles sticky or rough. If mammalian blood be treated with
one-seventh of its volume of solution of sodic sulphate, or if frog's blood be mixed
with a two per cent, solution of sugar and filtered, the shrivelled corpuscles, now
robbed of part of their water, remain upon the filter.

PHYSICAL PROPERTIES OF THE BLOOD.

(2.) Reaction. The reaction is alkaline, owing to the presence of
disodic phosphate, Na 2 ,H,P0 4 (Maly). After blood is shed, its
alkalinity rapidly diminishes, and this occurs more rapidly the greater
the alkalinity of the blood. This is due to the formation of an acid, in
which, perhaps, the coloured corpuscles take part, owing to the decom-
position of their colouring-matter. A high temperature and the addi-
tion of an alkali favour the formation of the acid (N. Zuntz).

The alkalinity is less in persons suffering from anremia, cachectic conditions,
and chronic rheumatism (Lgpine). After the prolonged use of soda, the alkali
in the ash of blood is increased (Dubelir).

Methods. Owing to the colour of the blood we cannot employ ordinary litmus
paper to test its reaction. One or other of the following methods may be used :
(1.) Moisten a strip of glazed red litmus paper with solution of common salt, and
dip it quickly into the blood, or allow a drop of blood to fall on the paper, and
rapidly wipe it off before its colouring-matter has time to penetrate and tinge the
paper (Zuntz). (2.) Kiihne made a small cup of parchment paper which was
placed in water in a watch-glass. The colourless diffusate was afterwards tested
with litmus paper. (3.) Liebreich used thin plates of plaster-of- Paris of a per-
fectly neutral reaction. These are dried, and afterwards moistened with a neutral
solution of litmus. When a drop of blood is placed upon the porous plate, the
fluid part of the blood passes into it, while the corpuscles remain at the surface.
The corpuscles are washed off with water, and the altered colour of the litmus-
stained slab is apparent. [(4.) Schiifer uses dry faintly -reddened glazed litmus
paper, and on it is placed a drop of blood, which is wiped off after a few seconds.
The place where the blood rested is indicated by a well-defined blue patch upon
a red or violet ground.]

The alkaline reaction of blood is diminished : () By great muscular exertion,
owing to the formation of a large amount of acid in the muscles ; (ft) during
coagulation ; (y) in old blood, or blood dissolved by water from old blood-stains,
such blood being usually acid. Fresh cruor has a stronger alkaline reaction than
serum.

(3.) Odour. Blood emits a peculiar odour (Halitm sanguinis), which
differs in animals and man.

It depends upon the presence of volatile fatty acids. If concentrated sulphuric
acid be added to blood, whereby the Volatile fatty acids are set free from their com-
binations with alkalies, the characteristic odour becomes much more perceptible
(Barruel).

(4.) Taste. Blood has a saline taste, depending upon the salts dis-
solved in the fluid of the blood.

(5.) Specific Gravity. The specific gravity is 1,055 (extreme limits
1,0451,075); in women and young persons it is somewhat less.
The specific gravity of the blood-corpuscles is 1,105, that of the
plasma 1,027. Hence, the corpuscles tend to sink.

The specific gravity of the red blood-corpuscles is estimated by allowing the
corpuscles to subside to the bottom (which occurs most readily in the blood of
the horse) ; but it is more correctly estimated by placing the blood in a tall
cylindrical vessel, and setting the latter in the radiiis of the revolving
disc of a centrifugal apparatus, the base of the cylinder being directed out-
wards. The drinking of water and hunger diminish the specific gravity tern-

MICROSCOPIC EXAMINATION OF THE ELOOD. 3

porarily, while thirst and the digestion of dry food raise it. If blood be passed
through an organ artificially, its specific gravity rises in consequence of the
absorption of dissolved matters and the giving off of water. It falls after
haemorrhage, and is less in badly-nourished individuals.

2. Microscopic Examination of the Blood.

[Blood, when examined by the microscope, is seen to consist of an
enormous number of corpuscles coloured and colourless floating in
a transparent fluid, the plasma, or liquor wnguinis.]

The RED blood-corpuscles were discovered in frog's blood by Swam-
merdam in 1658, and in human blood by Leeuwenhoek in 1673.

Characters of Human Blood (.) Form. The human red blood-
corpuscles are circular, coin-shaped, homogeneous discs, with saucer-like
depressions on both surfaces, and with rounded margins; in other
words, they are bi-concave, circular discs.

(5.) Size. According to Welcker the diameter (a b) is 7'7 JJL* the
greatest thickness (c d} 1/9 /x (Fig. 1, C) [i.e., it is -^^ to ^^^ of
an inch in diameter, and about one-fourth of that in thickness].

The corpuscles are slightly diminished in size by septic fever, inanition, after the
subcutaneous injection of morphia, increased bodily temperature, and C0 2 ; while
they are increased by O, watery condition of the blood, cold, consumption of
alcohol, quinine, hydrocyanic acid, and acute anpemia (Manassei'n).

A B

L

A, Human coloured blood-corpuscles 1, seen on the flat; 2, on edge; 3,
rouleau of coloured corpuscles slightly separated. B, Coloured amphibian
blood-corpuscles 1, seen on the flat, and 2, on edge. C, Ideal transverse
section of a human coloured blood-corpuscle magnified 5,000 times linear ;
a b, diameter ; c d, thickness.

* The Greek letter ju represents one-thousandth of a millimetre (/u = 0'001 mm.),
and is the sign of a micro-millimetre, or a micron.

MICROSCOPIC EXAMINATION OF THE BLOOD.

If the total amount of blood in a man be taken at 4,400 cubic centimetres, the
corpuscles therein contained have a surface of 2,816 square metres, which is equal
to a square surface with a side of 80 paces ; 176 cubic centimetres of blood pass
through the lungs in a second, and the blood-corpuscles in this amount of blood
have a superficies of 81 square metres, equal to a square surface with a side of 13
paces (Welcker).

(c.) Weight. The weight of a blood-corpuscle, according to Welcker,
is O'OOOOS milligrammes.

(?/.) Number. According to Vierordt, the number exceeds 5,000,000
per cubic millimetre in the male, and 4,500,000 in the female; so that,
in 10 Ib.s. of blood, there are 25 billions of corpuscles.

The venous blood of the small cutaneous veins contains more red
corpuscles than arterial blood. As a general rule, the number is in
inverse ratio to the amount of plasma ; hence, the number must vary
with the state of contraction of the blood-vessels, the pressure-diffusion
currents, and other conditions. The use of solid food increases their

B

If

Ibaa-Si) ' .
500-101 C

.L

^s

llong.-vo/um

1

Fig. 2.

Apparatus of Malassez for estimating the number of blood-corpuscles. A, the
mdangeur, or pipette, for mixing the blood with the artificial serum. /, tube
for sucking up these fluids. B, the artificial capillary tube, with an elastic
tube, /, attached for filling it. C, appearance of B under the microscope
when it is filled with blood. The squares are due to a piece of glass divided
into squares, which is put in the ocular of the microscope.

NUMBER OF BLOOD-CORPUSCLES. 5

number, copious draughts of water reduce it; during inanition the
number is relatively increased, because the blood plasma undergoes
decomposition sooner than the blood-corpuscles themselves (Buntzen).
The blood of the newly-born child contains a considerably larger number
of red corpuscles than the blood of the mother (Panum), while Hayem
found that the number diminished after the fourth day. In persons of
robust constitution the number is larger than in the weakly, and those
who live in the country have more than those who live in town.

(The pathological conditions which affect the number of corpuscles .
are given at p. 22).

a. Malasse^s Method of Estimating the number of Blood-Corpuscles. The
pointed end of a glass pipette (Fig. 2, A), the mixer, is dipped into the blood, and
by sucking the elastic tube, /, blood is drawn into the tube until it reaches the
mark, 4> on the stem of the pipette, or until the mark, 1, is reached. The
carefully-cleaned point of the pipette is dipped into the artificial serum, and this
is sucked into the pipette until it reaches the mark, 101. The artificial serum
consists of 1 vol. of solution of gum arabic (S. G. 1,020) and 3 vols. of a solution
of equal parts of sodic sulphate and sodic chloride (S. G. 1,020). The process of
mixing the two fluids is aided by the presence of a little glass ball (a) in the bulb
of the pipette. If blood is sucked up to the mark, |, the strength of the mixture
is 1:200; if to the mark, 1, it is 1:100. A small drop of the mixture is
allowed to run into the artificial capillary tube (c c) (the first portions are not
used in order to obtain a uniform sample from the bulb of the pipette). The
mixture passes by capillarity into the capillary tube, which, when full, is emptied
by blowing through the thin caoutchouc tube, /", and then again rilled to ,
and the mixture sucked into the middle of the capillary tube. The capillary tube
is firmly fixed to a glass slide (B) with Canada balsam, and on it is inscribed the
following numbers :

Length. Volume.

600 yu . 89

500 M . . . . 107

400 M . . . . 134

i.e., a length of the capillary tube of GOO, 500, and 400 M contains - a) 1 | r , -5-^,
cubic millimetre.

In order to count the corpuscles, the same combination of lenses must always be
used. Select Hartnack's objective, No. 5 (Nachet, No. 2) ; the ocular contains a
piece of glass divided into 100 squares. The tube of the microscope must be so
made that it can be pulled out and in. A micrometer, divided into -^fa milli-
metre, is placed upon the stage of the microscope : 1 division, therefore, 10 M
(p = i-,^ millimetre). The tube is now pulled out until the outer lines of the
divided ocular (tt, ii) exactly cover 600, 500, or 400 ;*. (500 M = k mm - i 3 most
convenient). A mark is made on the tube of the microscope to indicate how far
it must be drawn out to accomplish this object, and, having been made, it indicates,
once for all, how far the tube must be drawn out to indicate exactly 500 M. The
capillary tube is then filled and placed on the stage, instead of the micrometer,
when a picture like C is obtained. The length of the capillary tube, from tt to i i,
is 500 ju. All the corpuscles observable between t t and i i are now counted.
Suppose 315 corpuscles to be counted between 1 1 and i i, the number, 315, is then
multiplied by 107 (which stands opposite 500 on B) and also by 100 (when the
mixture of blood and serum was 1 : 100), or by 200 as the case may be i.e.,

NUMBER OF BLOOD-CORPUSCLES.

315 x 107 x 100 = 3,370,000 blood-corpuscles in 1 cubic millimetre. (After the
experiment the instruments must be carefully washed with distilled water. )

To estimate the colourless corpuscles only, mix the blood with 10
parts of 0'5 per cent, solution of acetic acid, which destroys all the red
corpuscles (Thoma).

Various forms of apparatus for the same purpose have been devised by Thoma,
Zeiss, Abbe", and Gowers.

[The following is a description of Gowers' instrument (Fig. 3): "The
Hcemacytometer consists of (1.) A small pipette, which, when filled to the
mark on its stem, holds exactly 995 cubic millimetres. It is furnished with
an India-rubber tube and mouthpiece to facilitate filling and emptying. (2.) A
capillary tube marked to contain exactly 5 cubic millimetres, with India-rubber
tube for filling, &c. (3.) A small glass jar in which the dilution is made. (4.) A
glass stirrer for mixing the blood and solution in the glass jar. (5.) A brass stage
plate, carrying a glass slip, on which is a cell, -J- of a millimetre deep. The bottom
of this is divided into -^ millimetre squares. Upon the top of the cell rests the
cover glass, which is kept in its place by the pressure of two springs proceeding
from the ends of the stage plate. "

The diluting solution used is a solution of sodic sulphate in distilled water,
S. G. 1,025, or the following sodic sulphate, 104 grains; acetic acid, 1 drachm;
distilled water, 4 ozs.

Fig. 3.

Gowers' apparatus, made by Hawksley, London. A, Pipette for measuring the
diluting solution. B, Capillary tube for measuring the blood. C, Cell with
divisions on the floor, mounted on a slide, to which springs are fixed to secure
the cover glass. I). Vessel in which the solution is made. E, Spud for
mixing the blood and solution. F, Guarded spear-pointed needle.

" 995 cubic millimetres of the solution are placed in the mixing jar; 5 cubic
millimetres of blood are drawn into the capillary tube from a puncture in the

HISTOLOGY OP THE RED BLOOD-CORPUSCLES. 7

finger, and then blown into the solution. The two fluids are well mixed by
rotating the stirrer between the thumb and finger, and a small drop of this dilution
is placed in the centre of the cell, the covering glass gently put upon the cell, and
secured by the two springs, and the plate placed upon the stage of the microscope.
The lens is then focussed for the squares. lu a few minutes the corpuscles have
sunk to the bottom of the cell, and are seen at rest on the squares. The number
in ten squares is then counted, and this, multiplied by 10,000, gives the number
in a cubic millimetre of blood. "

Welcker attempted to ascertain the number of corpuscles by estimating the
colouring-power of the blood. His method was not exact, but other observers
have constructed apparatus for determining the amount of haemoglobin.

(.) Ked blood-corpuscles are characterised by their great ELASTICITY,
FLEXIBILITY, and SOFTNESS. [The elastic property is shown by the
great extent to which red corpuscles still within the circulation may be
distorted, and yet resume their original form as soon as the pressure
is removed.]

3. Histology of the Human Red Blood-Corpuscles.

Wheu observed singly, blood-corpuscles have a yellow colour with
a slight tinge of green ; they seem to be devoid of an envelope, are
certainly non-nucleated, and appear to be homogeneous throughout.
Each corpuscle consists (1.) of a framework, an exceedingly pale, trans-
parent, soft protoplasm the stroma (Kollett) ; and (2.) of the red
pigment, or haemoglobin, which impregnates the stroma, much as
fluid passes into and is retained in the interstices of a bath-sponge.
Some observers (Bottcher, Eberhardt, Strieker), maintain that the
corpuscles contain a nucleus, but this is certainly a mistake.

4. Effects of Reagents.

(A.) Vital Phenomena. Blood-corpuscles contained in shed blood
or even in defibriiiated blood, when it is reintroduced into the circula-
tion retain their vitality and functions undiminished. Heat acts
powerfully on their vitality, for if blood be heated to 52C., the
vitality of the red corpuscles is extinguished. Mammalian blood may
be kept for four or live days in a vessel under iced water, and still
retain its functions ; but if it be kept longer, and reintroduced into
the circulation, the corpuscles rapidly break up a proof that they
have lost their vitality (Laudois). Blood freshly shed from an artery,
frequently shows a transformation of the corpuscles into a peculiar
mulberry-shape. [This is the so-called crenation of the coloured cor-
puscles. It is produced by poisoning with Calabar bean (T. E. Fraser),
and also by the addition of a 2 per cent, solution of common salt]. The

HISTOLOGY OF THE RED BLOOD-CORPUSCLES.

blood of many persons crenates spontaneously a condition ascribed
to an active contraction of the stroma (Klebs), but it is doubtful if
this is the cause. Max Schultze observed that the red corpuscles
of the embryo-chick undergo active contraction.

(B.) External Characters. Many agents affect the external char-
acters of the corpuscles.

(a.) The Colour is changed by many gases. makes blood scarlet,
want of renders it dark bluish-red, CO makes it cherry-red, NO
violet-red. There is no difference between the shape of corpuscles in
arterial and venous blood, as was supposed by Harless. All reagents
(e.g., a concentrated solution of sodic sulphate), which cause great
shrinking of the coloured corpuscles, produce a very bright scarlet or
brick-red colour (Bartholinus, 1661). The red colour so produced
is quite different from the scarlet-red of arterial blood. Keagents
which render blood-corpuscles globular darken the blood, e.g., water.
[The contrast is very striking, if we compare blood to which a 10 per
cent, solution of common salt has been added with blood to which
water has been added. With reflected light the one is bright-red,
and the other a very dark deep crimson, almost black.]

(b.) Change of Position and Form. A very common phenomenon
in shed blood is the tendency of the corpuscles to run into rouleaux
(Fig. 1, A, 3).

Conditions that increase the coagulability of the blood favour this phenomenon,
which is ascribed by Dogiel to the attraction of the discs and the formation of a
sticky substance. [The cause of the arrangement of the red corpuscles into
rouleaux is by no means clear. They may be detached from each other by gently
touching the cover-glass, but the rouleaux may reform. Lister suggested that
the surfaces of the corpuscles were so altered that they became adhesive, and thus
cohered. Norris has made some ingenious experiments with corks weighted with
tacks or pins, so as to produce partial submersion of the cork discs. These discs
rapidly cohere, owing to capillarity, and form rouleaux. If the discs be com-
pletely submerged they remain apart, as occurs with unaltered blood-corpuscles
within the blood-vessels. If, however, the corpuscles be dipped in petroleum,
and then placed in water, rouleaux are formed]. If reagents which cause the
corpuscles to swell up be added to the blood, the corpuscles become globular and
the rouleaux break up. According to E. Weber and Suchard, the uniting medium
is not fibrin (although it may sometimes assume a fibrous form), but belongs to the
peripheral layer of the corpuscles.

(c.) The Changes of Form which, after blood is shed, the red corpuscles
undergo until they are gradually dissolved, are important. Some reagents
rapidly produce this series of events e.g., the discharge of a Leyden jar
causes the corpuscles to crenate, so that their surfaces are beset with
large or small projections (Fig. 4, c, d, e, g, h); it also causes the corpuscles
to assume a spherical form (/,*), when they are smaller than normal.
The corpuscles so altered are sticky, and run together like drops of oil,

CHANGES IN THE FORM OF THE RED BLOOD-CORPUSCLES. 9

forming larger spheres. The prolonged action of the electrical spark
causes the haemoglobin to separate from the stroma (&), whereby the
fluid part of the blood is reddened, while the stroma is recognisable
only as a faint shadow (/). Similar forms are to be found in decom-
posing blood, as well as after the action of many other reagents.

Fig. 4.

Red blood-corpuscles, showing various changes of shape a, b, normal human red
corpuscles, with the central depression more or less in focus; c, d, e, mulberry
forms; g, h, crenated corpuscles; Tc, pale decolourised corpuscles; I, stroma;
/, a frog's blood-corpuscle, partly shrivelled, owing to the action of a strong
saline solution.

Action of Heat. When blood is heated, on a warm stage, to 52C.
the corpuscles begin to undergo remarkable changes. Some of them
become spherical, others biscuit-shaped ; some are perforated, while in
others small portions become detached and swim about in the surround-
ing fluid, a proof that heat destroys the histological individuality of
the corpuscles (Max Schultze). If the heat be continued, the corpuscles
are ultimately dissolved.

Cytozoon or Wurmchen Gaule's Experiment. The following remarkable

observation made by Gaule deserves mention here : A few drops of freshly-
shed frog's blood are mixed with 5 cc. of 0'6 per cent, solution of common salt,
and the mixture deh'brinated by shaking it along with a few cc. of mercury. A
drop of the defibrinated blood is examined on a hot stage (30-32C.) under a
microscope, when a protoplasmic mass, the so-called "wiirmcJien," escapes with
a lively movement from many corpuscles, and ultimately dissolves. Similar
"cytozoa" were discovered by Gaule in the epithelium of the cornea, of the
stomach and intestine, in connective tissue, in most of the large glands, and in the
retina (frog, triton). In mammals also he found similar but smaller structures.
Most probably these structures are parasitic in their nature, as suggested by
R,ay Lankester, who called the parasite Drepanidium ranartim.

If a finger moistened with blood be rapidly drawn across a warm
slip of glass, so that the fluid dries rapidly, very remarkable corpuscle-
shapes, showing their great ductility and softness, are observed under
the microscope.

10 LAKE-COLOURED BLOOD.

If blood be mixed with concentrated gum, and if concentrated salt solution be
added to it under the microscope, the corpuscles assume elongated forms
(Lindwurm). (Similar forms are obtained by mixing blood with an equal volume
of gelatine at 3GC., allowing it to cool, and then making sections of the coagulated
mass (Rollett). The corpuscles may be broken up by pressing firmly on the
cover-glass. In all these experiments no trace of an envelope is observed.

5. Preparation of the Stroma Making Blood

"Lake-Coloured."

There are many reagents which separate the haemoglobin from the
stroma. The hemoglobin dissolves in the serum ; the blood then
becomes transparent, as it contains its colouring matter in solution, and
hence it is called " lake-coloured " by Rollett. Lake-coloured blood is
dark-red. The aggregate condition of the hsemoglobin is not altered,
when the corpuscles are dissolved it only changes its place, leaving the
stroma and passing into the serum. Hence, the temperature of the
blood is not lowered thereby (Landois). To obtain a large quantity
of the stroma, add ten volumes of a solution of common salt (1 vol.
concentrated solution, and 15 to 20 vols. of water) to one volume of
defibriuated blood, when the stromata are thrown down as a whitish
precipitate.

The following reagents cause a separation of the stroma from the haemo-
globin :

(a.) Physical Agents. 1. Heating the blood to 60C. (Schultze); the tempera-
ture, however, varies for the blood of different animals. 2. Eepeated freezing
and thawing of the blood (Rollett). 3. Sparks from an electrical machine (but
not after the addition of salts to the blood) (Eollett); the constant and induced
currents (Neumann).

(b.) Chemically active Substances produced within the Body. 4. Bile

(Hiinefeld), or bile salts (Plattner, v. Dusch). 5. Serum of other species of
animals (Landois); thus dog's serum and frog's serum dissolve the blood-corpuscles
of the rabbit in a few minutes. 6. The addition of lake-coloured blood of many
species of animals (Landois).

(c.) Other Chemical Reagents. 7. Water. 8. Conduction of vapour of
chloroform (Bottcher); ether (v. Wittich); amyls, small quantities of alcohol
(Rollett); thymol (Marchand); nitrobenzol, ethylic ether, aceton, petroleum
ether, etc. (L. Lewin). 9. Antimonuretted hydrogen, arseuiuretted hydrogen ;
carbon disulphide (Hiiuefeld, Hermann); boracic acid (2 per cent.), added to amphi-
bian blood, causes the red mass (which also encloses the nucleus when such is pre-
sent), the so-called zoold, to separate from the axoid. The zooid may shrink from
the periphery of the corpuscle, or it may even pass out of the corpuscle altogether
(Briicke) ; Briicke regards the stroma in a certain sense as a house, in which the
remainder of the substance of the corpuscle, the chief part endowed with vital
phenomena, lives. 11. Strong solutions of adds dissolve the corpuscles; more
dilute solutions cause precipitates in the haemoglobin. This is easily seen with
carbolic acid (Hiils and Landois; Stirling and Rannie). 12. Alkalies of moderate
strength cause sudden solution. A 10 per cent, solution of potash, placed at the
margin of a cover-glass, shows the process of solution going on under the micro-

FORM AND SIZE OF THE BLOOD-CORPUSCLES.

11

scope. At first the corpuscles become globular, and so appear smaller, but after-
wards they burst like soap-bubbles.

[Tannic Acid. A freshly prepared solution of tannic acid has a remarkable
effect on the coloured blood-corpuscles of man and animals causing a separa-
tion of the haemoglobin and the stroma. The usual effect is to produce one or
more granular buds of haemoglobin on the side of the corpuscles ; more rarely
the haemoglobin collects around the nucleus, if such be present (W. Roberts).]

[Ammonium or Potassium Sulpho-Cyanide removes the haemoglobin, and
reveals areticular structure infra-nuclear plexus of fibrils (Stirling and Rannie).]

The quantity of gases contained in the blood-corpuscles exercises
an important influence on their solubility. The corpuscles of venous
blood, which contains much C0 2 , are more easily dissolved than
those of arterial blood; while between both stands blood containing
CO (Laudois, Litterski). When the gases are completely removed
from the blood, it becomes lake-coloured.

6. Form and Size of the Blood- Corpuscles of
Different Animals.

All mammals (with the exception of the camel, llama, alpaca, and
their allies), and the cyclostomata amongst fishes e.g., Petromyzon,
possess circular disc-shaped corpuscles.

Elliptical corpuscles without a nucleus are found in the above-named
mammals, while all birds, reptiles, amphibians (Fig. 1, B, 1, 2), and fishes
(except cyclostomata) have nucleated elliptical bi-convex corpuscles.

Size (n - O'OOl Millimetre)

Of the Disc-shaped
Corpuscles.

Of the Elliptical Corpuscles.

Short Diameter.

Long Diameter.

Elephant, . 0'0094 Mm.
Man, . .0-0077,
Dog, . . 0-0073 ,
Rabbit, . 0'0069 ,
Cat, . . . 0-0065 ,
Sheep, . . 0-0050 ,
Goat, . . 0-0041 ,
Musk-deer, 0-0025 ,

Llama, '0040 Mm.
Dove, 0-0065 ,,
Frog, 0-0157
Triton, 0'0195
Proteus, 0-035 ,,

The corpuscles of An
third larger than those of

0-0080 Mm.
0-0147
0-0223 ,,
0-0293
0-058 ,,

.pliiuma are nearly one-
Proteus (Riddel).

Amongst vertebrates, amphioxus has colourless blood invertebrates generally
have colourless blood, with colourless corpuscles ; but the earth-worm, and the
larva of the large gnats, &c. , have red blood whose plasma contains haemoglobin,
while the blood-corpuscles themselves are colourless.

[Elaborate measurements of the blood-corpuscles have been made in

12 ORIGIN OF THE RED BLOOD-CORPUSCLES.

this country by Gulliver, but the relative size may be best appreciated
by comparing the corpuscles from various vertebrates.]

Many invertebrates possess red, violet, brown, or green opalescent blood with
colourless corpuscles (amoeboid cells). In cephalopods, and some crabs, the blood
is blue, owing to the presence of a colouring-matter (Hcemo-cyanln) which, con-
tains copper, and combines with O (Bert, Kabuteau & Papillon, Fre"dericq, and
Krukeuberg). The large blood-corpuscles of many amphibia, e.g., amphiuma, are
visible to the naked eye. The blood-corpuscles of the frog contain, in addition to
a nucleus, a micleolus (Auerbach, Ranvier), [and the same is true of the coloured
corpuscles of the newt (Stirling). The nucleolus is revealed by acting on the
corpuscles with dilute alcohol (1, alcohol; 2, water; Ranvier's "a!cool au tiers").'}
It is evident that the larger the blood-corpuscles are, the smaller must be the number
and total superficies of corpuscles in a given volume of blood. In birds, how-
ever, the number is relatively larger than in other classes of vertebrates, notwith-
standing the larger size of their corpuscles ; this, doubtless, has a relation to the
very energetic metabolism that takes place in birds (Malassez).

Amongst mammals, caruivora have more blood-corpuscles than herbivora.
Welcker has ascertained that goat's blood contains 9,720,000 corpuscles per cubic
millimetre; the llama's, 13,000,000; the bullfinch's, 3,600,000; the lizard's,
1,420,000; the frog's, 404,000; the proteus', 36,000. In liybernatinrj animals,
Vierordt found that the number of corpuscles diminished from 7,000,000 to
2,000,000 per cubic millimetre during hybernation.

7. Origin of the Red Blood-Corpuscles.

(A.) Origin of the Nucleated Red Corpuscles during Embryonic
Life. Blood-corpuscles are developed in the fowl during the first days
of embryonic life. [They appear in groups within the large branched
cells of the mesoblast, in the vascular area of the blastoderm outside
the developing body of the chick or embyro, where they form the
" Hood-islands " of Pander. The mother-cells form an irregular net-
work by the union of the processes of adjoining cells, and meantime
the central masses split up, and the nuclei multiply. The small
nucleated masses of protoplasm, which represent the blood-corpuscles,
acquire a reddish hue, while the surrounding protoplasm, and also that
of the processes, becomes vacuolated or hollowed out, constituting a
branching system of canals ; the outer part of the cells remaining with
their nuclei to form the walls of the future blood-vessels. A fluid
appears within this system of branched canals in which the corpuscles
lie, and gradually a communication is established with the blood-
vessels developed in connection with the heart.]

[According to Klein, the nuclei of the protoplasmic wall may also
proliferate, and give rise to new corpuscles, which are washed away to
form blood-corpuscles.] At first the corpuscles are devoid of pigment,
nucleated, globular, larger and more irregular than the permanent
corpuscles, and they also exhibit amoeboid movements. They become

ORIGIN OF THE RED BLOOD-CORPUSCLES. 13

coloured, retain their nucleus, and are capable of undergoing multipli-
cation by division ; and, in fact, Remak observed all the stages of the
process of division. The process of division is best seen from the 3rd
5th day of incubation. Increase by division also takes place in the
larvre of the salamander, triton, and toad (Flemming, Peremeschko).

After the liver is developed, blood-corpuscles seem to be formed in it
(E. H. Weber, Kolliker). Protoplasmic, nucleated, colourless cells are
carried by the vena porta from the spleen into the liver, where they
take up pigment. Neumann found in the liver of the embryo proto-
plasmic cells containing red blood-corpuscles. The spleen is also
regarded as a centre of their formation, but this seems to be the case
only during embryonic life (Neumann). Here the red corpuscles are
said to arise from yellow, round, nucleated cells, which represent
transition forms. Foa and Salvioli found red corpuscles forming
endogenously within large protoplasmic cells in lymphatic glands. In
the later period of embryonic life, the characteristic non-nucleated
corpuscles seem to be developed from the nucleated corpuscles. The
nucleus becomes smaller and smaller, breaks up, and gradually dis-
appears. In the human embryo at the fourth week only nucleated
corpuscles are found ; at the third month their number is still }-|- of
the total corpuscles, while at the end of fetal life nucleated blood-
corpuscles are very rarely found. Of course, in animals with nucleated
blood-corpuscles, the nucleus of the embryonic blood-corpuscles remains.

(B.) Development of Blood-Vessels, Formation of Blood- Vessels and
Blood-Corpuscles during Post-embryonic Life. Kolliker assumed
that, in the tail of the tadpole, capillaries are formed by the anasto-
moses of the processes of branched and radiating connective tissue-
corpuscles. These corpuscles lose their nuclei and protoplasm, become
hollowed out, join with neighbouring capillaries, and thus form new
blood-channels. Von Golubew, on the other hand, opposes this view.
He assumes that the blood capillaries in the tail of the tadpole give off
solid buds at different places, which grow more and more into the
surrounding tissues, and anastomose with each other ; their protoplasm
and contents disappearing, they become hollow and a branched
system of capillaries is formed in the tissues. Eanvier, be it remarked,
noticed the same mode of growth in the omentum of newly-born
kittens.

The latter observer has recently studied the development of blood-
vessels and blood-corpuscles in the omentum of young rabbits. These
animals, when a week old, have, in their omentum, little white or
milk spots (" taches laiteiises," Ranvier), in which lie " vaso-formative "
cells, i.e., highly refractive cells of variable shape, with long cylindrical
protoplasmic processes (Fig. 5). In its refractive power the protoplasm

14

ORIGIN OF THE RED BLOOD-CORPUSCLES.

of these cells resembles that of lymph-corpuscles. Long rod-like

nuclei lie within these
cells (K, K), and also
red blood - corpuscles
(r, r), and both are sur-
rounded with proto-
plasm. These vaso-
formative cells give off
points
(a, a),

Fig. 5.

protoplasmic
and processes
some of which end
free, while others form

a network. Here and
Formation of red blood-corpuscles within "vaso-

formative cells," from the omentum of a rabbit there elongated COn-
seven days old. r, r, the formed corpuscles. K, K, nective tissue-corpus-
nucleiof the vaso-formative cell, a, a, processes cles lie Oil the branches,
which ultimately unite to form capillaries. &nd ultimately form

the adventitia of the blood-vessel.

The vaso-formative cells have many forms : they may be elongated
cylinders ending in points, or more round and oval, resembling
lymph cells, or they may be modified connective tissue-corpuscles, as
observed by Schafer in the subcutaneous tissue of young rats. These
cells are always the scat of origin of non-nucleated red blood-corpuscles,
which arise in the protoplasm of vaso-formative cells, as chlorophyll
grains or starch granules arise within the cells of plants. The
corpuscles escape and are washed into the circulation, when the cells
form connections with the circulatory system by means of their pro-
cesses. It is probable that the vessels so formed in the omentum are
only temporary. May it not be that there are many other situations
in the body where blood is regenerated 1

[The observations of Schafer also prove the infra-cellular origin of
red blood-corpuscles, and although this mode usually ceases before
birth, still it is found in the rat at birth. The protoplasm of the
subcutaneous connective tissue-corpuscles, which are derived from the
mesoblast, has in it small coloured globules about the size of a
coloured corpuscle. The mother-cells elongate, become pointed at
their ends, and unite with processes from adjoining cells. The cells
become vacuolated ; fluid or plasma, in which the liberated corpuscles
float, appears in their interior, and ultimately a communication is
established with the general circulation.]

Similar observations have been made by Neumann in the embryonic liver ; by
Wissotzky in the rabbit's amnion ; by Klein in the embryo chick ; and by Leboucq
and Hayem in various animals ; all of which go to show that at a certain early

ORIGIN OF THE RED BLOOD-CORPUSCLES. 15

period of development blood-corpuscles are formed within other large cells of the
mesoblast, and that part of the protoplasm of these blood-forming cells remains to
form the wall of the future blood-vessel.

(C.) Later Formation of Red Blood-Corpuscles. There is much
diversity of opinion as to how coloured blood-corpuscles are formed in
mammals at a later period. [They have been described as derived from
colourless corpuscles, one set of observers (including Kolliker) main-
taining that the nucleus of these corpuscles disappears, while the
peri-nuclear portion remains, becomes flattened and coloured, and
assumes the characters of the mammalian blood-corpuscles. On the
other hand, other observers (including Wharton Jones, Gulliver, Busk,
Huxley, and Balfour) are of opinion that the nucleus becomes pigmented,
and forms the future blood-corpuscle. It is still doubtful, however,
whether coloured corpuscles are developed in either of these ways.]
Neumann and Bizzozero described peculiar corpuscles occurring in the
red marrow of bone, which they maintain become developed into
coloured blood-corpuscles, undergoing a series of changes, and forming
a series of intermediate forms, which may be detected in the red
marrow. Bizzozero holds that it is the nucleus of the marrow-cell
which is coloured, while Neumann thinks it is the perinuclear part
which becomes coloured, and forms the blood-corpuscle. Schafer's
observations on the red marrow of the guinea-pig rather tend to con-
firm Neumann's view.

These transition cells are said by Erb to be more numerous after
severe haemorrhage, the number of them occurring in the blood
corresponding with the energy of the formative process. In dogs
and guinea-pigs which he had rendered an?emic, Bizzozero found in the
marrow and spleen nucleated red blood-corpuscles, which increased by
division.

According to Neumann, the bone-matron 11 of adults contains all transi-
tion forms, from nucleated coloured corpuscles to true red blood-
corpuscles. After copious haemorrhage, these transition forms appear
in numbers in the blood-stream.

Red or blood-forming marrow occurs in the bones of the skull, and in most of the
bones of the trunk, while the bones of the extremities either contain yellow
marrow (which is essentially fatty in its nature), or, at most, it is only the heads
of the long bones that contain red marrow. Where the blood regeneration process
is very active, however, the yellow marrow may be changed into red, even through-
out all the bones of the extremities (Neumann).

Rindfleisch also regards the connective substance of the red marrow and the
spleen as the mother-tissue of the red. blood-corpuscles, the connective substance
or the hfematogenous connective tissue either temporarily or permanently forming
red blood-corpuscles. Once the red corpuscles are formed, they easily enter the
blood-stream, as the capillaries and veins of the red marrow have either no walls

16 DECAY OF THE RED BLOOD-CORPUSCLES.

(Hoyer, Kollmann), or exceedingly thin perforated walls. Similar conditions
obtain, in the spleen.

Bizzozero and Torre found that after severe haemorrhage in birds, the marroio of
the bones contained globular, granular, nucleated cells, whose protoplasm was
coloured with haemoglobin, while between these and the oval biconvex nucleated
corpuscles of the bird, there were numerous transition stages. The spleen of the
bird seems to be of much less importance in the formation of blood-corpuscles
(Korn). All these observations prove that the red marrow of the bones is a great
manufactory for coloured blood-corpuscles.

v. R-eckliughausen observed the direct transformation of these intermediate
forms into blood-corpuscles in frog's blood, which was kept for several days in a
moist chamber. A. Schmidt and Semmer found large lymph cells in the blood,
filled with granules of ha?mogoblin, and they regard these as intermediate forms
between colourless and coloured corpuscles.

[Malassez, from an investigation of the red marrow of young kids,
finds that the cells of the red marrow and certain cells in the spleen
form rounded coloured projections or buds on their surface. These
get detached and form young blood-corpuscles, which soon become
disc-shaped; while the mother-cell itself continues to produce other
coloured corpuscles. Thus gemmation of the splenic and medullary cells
constitutes one great process in the manufacture of blood-corpuscles.
Hence it is apparent why diseases of bone in children lead to ansemia,
and soon bring about a cachectic condition.]

8. Decay of the Red Blood-Corpuscles.

The blood-corpuscles must positively undergo decay within a limited
time, and the liver is regarded as one of the chief places in which
their disintegration occurs, because bile-pigments are formed from
haemoglobin, and the blood of the hepatic vein contains fewer red
corpuscles than the blood of the portal vein.

The splenic pulp contains cells which seem to indicate that coloured
corpuscles are broken up within it. These are the so-called "blood-
corpuscle-containing cells." Quincke's observations go to show that the
red corpuscles which may live from three to four weeks when about
to disintegrate, are taken up by white blood-corpuscles, and by the cells
of the spleen and the bone-marrow, and are stored up chiefly in the
spleen and marrow of bone. They are transformed, partly into
coloured, and partly into colourless proteids which contain iron, and
are either deposited in a granular form, or are dissolved. Part of the
products of decomposition is used for the formation of new blood-
corpuscles in the marrow and in the spleen, and also perhaps in the
liver, while a portion of the iron is excreted by the liver in the bile.

That the normal red blood-corpuscles and other particles suspended in the blood-
stream are not taken up in this way, may be due to their being smooth and polished.

THE COLOURLESS BLOOD-CORPUSCLES. 17

As the corpuscles grow older and become more rigid, they, as it were, are caught
by the amoeboid cells. As cells containing blood-corpuscles are very rarely found
in the general circulation, one may assume that the occurrence of these cells within
the spleen, liver, and marrow of bone is favoured by the slowness of the circulation
in these organs (Quincke).

Pathological- In certain pathological conditions, ferruginous substances
derived from the red blood-corpuscles are found in the spleen, in the marrow of
bone, and in the capillaries of the liver : (1.) When the disintegration of blood-
corpuscles is increased, as in ana?mia (Stahel). (2.) When the formation of red
blood-corpuscles from the old material is diminished. If the excretion from the
liver cells be prevented, iron accumulates within them ; it is also more abundant in
the blood-serum, and it may even accumulate in the secretory cells of the cortex of
the kidney and pancreas, in gland cells, and in the tissue elements of other organs
(Quincke). When the amount of blood is greatly increased (in dogs), after four
weeks an enormous number of granules containing iron occur in the leucocytes of
the liver capillaries, the cells of the spleen, bone-marrow, lymph-glands, the liver
cells, and the epithelium of the cortex of the kidney (Quincke). The iron reaction
in the two last situations occurs after the introduction of hemoglobin, or of salts
of iron into the blood (Glaeveck and v. Stark).

When we reflect how rapidly (relatively) large quantities of blood
are replaced after haemorrhage and after menstruation, it is evident
that there must be a brisk manufactory somewhere. As to the number
of corpuscles which daily decay, we have in some measure an index
in the amount of bile-pigment and urine-pigment resulting from the
transformation of the liberated hemoglobin.

9. The Colourless Corpuscles (Leucocytes).

Blood, like many other tissues, contains a number of cells or cor-
puscles which reach it from without; the corpuscles vary somewhat
in form, and are called colourless or ivhitfi blood-corpuscles, or " leucocytes "
(Hewson, 1770). Similar corpuscles are found in lymph, adenoid
tissue, marrow of bone, as wandering cells or leucocytes, in connective
tissue, ami also between glandular and epithelial cells. They all con-
sist of more or less spherical masses of protoplasm, which is sticky,
highly refractile, soft, capable of movement, and devoid of an envelope
(Fig. 6). When they are quite fresh (A) it is difficult to detect the
nucleus, but after they have been shed for some time, or after the
addition of water (B), or acetic acid, the nucleus (which is usually
a compound one) appears ; acetic acid clears up the perinuclear proto-
plasm, and reveals the presence of the nuclei, of which the number
varies from one to four, although generally three are found. The
subsequent addition of magenta solution- stains the nuclei deeply.
Water makes the contents more turbid, and causes the cor-
puscles to swell up. One or more nucleoli may be present in the
nucleus. The corpuscles contain proteids, but they also contain fats,
lecithin, and salts (p. 37). The size of the corpuscles varies from four

2

18

THE COLOURLESS BLOOD-CORPUSCLES.

to thirteen //, and as a rule they are about

Fig. 6.

of an inch in diameter,
and in the smallest
the layer of the pro-
toplasm is extremely
thin. They all have
the property of ex-
hibiting amoeboid
movements which are
very apparent in the
larger corpuscles.

These movements AV ere
discovered by Wharton
Jones in the skate, and
by Davine in the cor-
puscles of man. Max
Schultze describes
three different forms
in human blood :

(1.) The smallest,

White blood-corpuscles A, Human, without the addi- , f -, ,-,

, , , ,. . ,. round lorms, less man
tion of any reagent. 13, alter the addition ot i i.

water, nuclei visible. C, after the action of acetic tne rec <- corpuscles, AVlth

acid. D, Frog's corpuscles showing changes of one to two nuclei, and

shape due to amceboid movement. E, Fibrils of a ver y small amount of
fibrin from coagulated blood. F, Fjlementary

granules. protoplasm ;

(2.) Round forms,
the same size as the coloured blood-corpuscles ;

(3.) The large amoeboid corpuscles, \vith much protoplasm and
distinctly evident movements.

[When a drop of human blood is examined under the microscope,
more especially after the coloured blood-corpuscles have run into
rouleaux, the colourless corpuscles may readily be detected, there
being usually three or four of them visible in the field at once.
They adhere to the glass slide, for if the cover-glass be moved, the
coloured corpuscles readily glide OA r er each other, while the colourless
can be seen still adhering to the slide.

White Corpuscles of Newt's Blood. The characters of the colourless
corpuscles are best studied in a drop of newt's blood. Cut off the tip
of the tail and express a drop of blood on to a slide, cover it with a
thin glass, and examine.

Neglecting the coloured corpuscles, search for the colourless, of which
there are three varieties :

(1.) The Large Finely Granular Corpuscle, Avhich is about -^ of an

THE COLOURLESS BLOOD-CORPUSCLES. 19

inch ill diameter, irregular in outline, with fine processes or pseudo-
podia, projecting from its surface. It rapidly changes its shape at the
ordinary temperature, and in its interior a bi- or tri-partite nucleus
may be seen, surrounded with fine granular protoplasm, whose outline
is continually changing. Sometimes vacuoles are seen in the proto-
plasm.

(2.) The Coarsely Granular Variety is less common than the first-
mentioned, but when detected its characters are distinct. The proto-
plasm contains, besides a nucleus, a large number of highly refractive
granules, and the corpuscle usually exhibits active amoeboid movements ;
suddenly the granules may be seen to rush from one side of the
corpuscle to the other. The processes are usually more blunt than
those emitted by (1). The relation between these two kinds of
corpuscles has not been ascertained.

(3.) The Small Colourless Corpuscles are more like the ordinary
human colourless corpuscle, and they, too, exhibit amoeboid move-
ments.

Two kinds of colourless corpuscles like (1.) and (2.) exist in frog's
blood. In the coarsely granular corpuscles the glancing granules may
be of a fatty nature, since they dissolve in alcohol and ether, but other
granules exist which are insoluble in these fluids, and the nature of
which is unknown. Very large colourless corpuscles exist in the
axolotl's blood (Ranvier).

Action of Reagents. (.) Water, when added slowly, causes the
colourless corpuscles to become globular, and the granules within them
to exhibit Brownian movements (Richardson, Strieker), (b.) Pigment*,
such as magenta or carmine, stain the nuclei very deeply, and the
protoplasm to a less extent, (c.) Dilute Acetic Acid clears up the
surrounding protoplasm and brings clearly into view the composite
nucleus, which may be stained thereafter with magenta, (d.) Iodine
gives a faint port-wine colour (horse's blood indicating the presence of
glycogen best), (e.) Dilute Alcohol causes the formation of clear blebs
on the surface of the corpuscles, and brings the nuclei clearly into view
(Eanvier, Stirling).]

[A delicate plexus of fibrils intra-nuclear plexus exists within the
nucleus just as in other cells. It is very probable that the protoplasm
itself is pervaded by a similar plexus of fibrils, and that it is continuous
with the intra-nuclear plexus.]

The colourless corpuscles divide, and in this way reproduce them-
selves (Klein).

The Number of Colourless Blood-Corpuscles is very much less than
that of the red corpuscles, and is subject to considerable variations.

It is certain that the colourless corpuscles are very much fewer in

20 AMfEBOID MOVEMENTS OF THE COLOURLESS CORPUSCLES.

shed blood than in blood still within the circulation. Immediately
after blood is shed, an enormous number of white corpuscles disappear
(SQQ Formation of Fibrin, p. 47).

Al. Schmidt estimates the number that remain at X V of the whole originally
present in the circulating blood. The proportion is greater in children than in
adults (Bouchut and Dubrisay).

The following table gives the number in shed blood :

NUMBER OF WHITE CORPUSCLES IN PROPORTION TO EED CORPUSCLES

In Normal Conditions.

In Different Places.

In Different Conditions.

1 : 335 (Welcker).
1 : 357 (Moleschott).

Splenic Vein, 1 : 60
Splenic Artery, 1 : 2,260
Hepatic Vein, 1 : 170
Portal Vein, 1 : 740
Generally more numerous
in Veins than Arteries.

Increased by
Digestion, Loss of Blood,
Prolonged Suppuration,
Parturition, Leukaemia,
Quinine, Bitters.

Diminished by
Hunger, Bad Nourishment,

The old method of Welcker for estimating the number of colourless corpuscles is
unsatisfactory. The blood was defibrinated, placed in a tall vessel, and allowed to
subside, when a layer of colourless corpuscles was obtained immediately under
a layer of serum. [It is better to use the liEemocytometer (p. 6) as improved by
Gowers.]

The Amoeboid Movements of the white corpuscles (so-called because
they resemble the movements of amoeba) consist in an alternate con-
traction and relaxation of the protoplasm surrounding the nucleus.
Processes are given off from the surface, and are retracted again (like
the pseudopodia of amoeba).

There is an internal current in the protoplasm, and the nucleus has
also been observed to change its form (Lavdowsky). Two series of
phenomena result from these movements: (1.) The "wandering" or
locomotion of the corpuscles due to the extension and retraction of
their processes ; (2.) the absorption of small particles into their interior
(fat, pigment, foreign bodies). The particles adhere to the sticky
external surface, are carried into the interior by the internal currents
(Preyer), and may eventually be excreted, just as particles are
taken up by amceba and the effete particles excreted. [Max Schultze
observed that coloured particles were readily taken up by these
corpuscles.]

On a hot stage (35-40C.) the colourless corpuscles of mammals
retain their movements for a long time ; at 40C. for two to three hours;
at 50C. the proteids are coagulated and cause "heat-rigor" and death.
In cold-blooded animals (frogs) colourless corpuscles may be seen to crawl

THE BLOOD-PLATES.

21

out of small coagula, in a moist chamber, and move about in the
serum. Induction shocks cause them to withdraw their processes and
become spherical, and, if the shocks be not too severe, their movements
recommence. Strong shocks kill them. is necessary for their
movements. These amoeboid movements are of special interest on
account of the "wandering out" (diapedesis) of colourless blood-
corpuscles through the walls of the blood-vessels (Waller, Cohnheim).

The chyle contains leucocytes, which are more resistant than those of the blood,
but less so than those of the coagulable transudations (Heyl). The leucocytes
of the lymphatic glands may also be dissolved (Rauscheubach).

Relation to Anililie Pigments. Ehrlich has observed a remarkable relation
of the white corpuscles to acid (eosin, picric acid, aurantia), basic (dahlia, acetate
of rosanilin), or neutral (picrate of rosanilin) reactions. The smallest protoplasmic
granules of the cells have different chemical affinities for these pigments. Thus
Ehrlich distinguishes "eosinophile," "basophile," and " neutrophile " granules
within the cells. Eosinophile granules occur in the leucocytes of amphibia, and
in the marrow of their bones. Human leucocytes exhibit a neutrophile reaction,
except in the case of those corpuscles that have large ovoid nuclei : the former
are said to be the early stage of the latter. The eosinophile corpuscles are greatly
increased in leukosmia. The basophile granules occur chiefly in connective tissue-
corpuscles and in the neighbourhood of epithelium they are always greatly
increased where chronic inflammation occurs.

III. Special attention has recently been directed to a third element

Fig. 7.

' ' Blood-plates " and their derivatives, partly after Bizzozero and Laker. 1, Red
blood-corpuscles on the flat. 2, From the side. 3, Unchanged blood-plates.
4, A lymph-corpuscle, surrounded with blood-plates. 5, Blood-plates
variously altered. G, A lymph-corpuscle with two heaps of fused blood-
plates and threads of fibrin. 7, Group of blood-plates fused or run together.
8, A similar small heap of partially dissolved blood-plates with fibrils of fibrin.

22 CHANGES OF THE RED AND WHITE BLOOD-CORPUSCLES.

of the blood, the " llood-platcs " of Bizzozero ; pale, colourless, biconcave
discs of variable size (mean, 3 /uC). According to Hayem (who called
these structures H^EMATOBLASTS, supposing that they were an early
stage in the development of the red blood-corpuscles), they are forty
times as numerous as the leucocytes. These blood-plates may be
recognised in circulating blood, as in the mesentery of the guinea-pig.
They are precipitated in enormous numbers upon threads suspended in
fresh-shed blood (Bizzozero). They may be obtained from blood
flowing directly from a blood-vessel, on mixing it with 1 per cent,
solution of osmic acid or Hayem's fluid (mercury bichloride 0'5, sodium
carbonate 5, sodium chlorate 1, distilled water 200 Laker). They
undergo a rapid change in shed blood (Fig. 7, 5), disintegrating,
forming small particles, and ultimately dissolving. When several occur
together they rapidly unite, form small groups (7), and collect into
masses resembling " stroma-fibrin " (p. 48). These masses may be
associated in coagulated blood with fibrils of fibrin.

Bizzozero believes that they yield the material for the formation of fibrin during
coagulation of the blood. It is not yet determined whether they are derived from
partially disintegrated leucocytes, or whether they are independent formations.
Along with the leucocytes they are concerned in the formation of fibrin (Hlava).
These structures were known to earlier observers (Max Sehultze, Puess, and
others) ; but their significance has been variously interpreted.

IV. Blood, especially after a microscopic preparation has been made
for a short time, is seen to contain ELEMENTARY GRANULES (Fig. 6, F),
[/.('., the elementary particles of Zimmermann and Beale. They are
irregular bodies, much smaller than the ordinary corpuscles, and appear
to consist of masses of protoplasm detached from the surface of
leucocytes, or derived from the disintegration of these corpuscles, or
of the blood-plates. Others, again, are completely spherical granules,
either consisting of some proteid substance or fatty in their nature.
The protoplasmic and the proteid granules disappear on the addition
of acetic acid, while the fatty granules (which are most numerous after a
diet rich in fats) dissolve in ether].

V. In COAGULATED blood, delicate fibrils or threads of FIBRIN (Fig.
G, E and G, S, G) are seen, more especially after the corpuscles have
run into rouleaux. At the nodes of these fibres are found granules
which closely resemble those described under III.

[These granules and fibres are stained by magenta and iodine, but
not by carmine or picro-carmine (Ranvier).]

10. Abnormal Changes of the Red and White
Blood-Corpuscles.

(1.) All haemorrhages diminish the number of red corpuscles (at most one-
half), and so does menstruation. The loss is partly covered by the absorption of

CHANGES OF THE RED AND WHITE BLOOD-CORPUSCLES. 23

fluid from the tissues. Menstruation shows us that a moderate loss of red cor-
puscles is replaced within twenty-eight days. When a large amount of blood is
lost, so that all the vital processes are lowered, the time may be extended to five
weeks. In acute fevers, as the temperature increases, the number of red corpuscles
diminishes, while the white corpuscles increase in number (Kiegel & Boeckmann).

(2.) Diminished production of new red corpuscles causes a decrease, since
blood-corpuscles are continually being used up. In chlorotic girls there seems to
be a congenital weakness in the blood-forming and blood-propelling apparatus, the
cause of which is to be sought for in some faulty condition of the rneso-blast. In
them the heart and the blood-vessels are small, and the absolute mimber of cor-
puscles may be diminished one-half, although the relative number may be retained,
while in the corpuscles themselves the haemoglobin is diminished almost one-third
(Duncan, Quincke) ; but it rises again after the administration of iron (Hayem).
The administration of iron increases the amount of haemoglobin in the blood
(Scherpf). The amount of iron in the blood maybe diminished one-half. [The
action of iron in anaemic persons has been known since the time of Sydenham.
Hayem also finds that in certain forms of anaemia there is considerable variation
in the size of the red corpuscles, and that in chronic anemia the mean diameter
of the corpuscles is always less than normal (7 M to 6 M). There is, moreover, a
persistent alteration in the volume, colouring power, and consistence of the cor-
puscles, consequently a want of accord between the number of the corpuscles and
their colouring power i.e., the amount of haemoglobin which they contain, as was
pointed out by Johaiui Duncan.] In so-called pernicious anwmia, in which the
continued decrease in the red corpuscles may ultimately produce death, there is
undoubtedly a severe affection of the blood-forming apparatus. The corpuscles
assume many abnormal and bizarre forms (microcytes), often being oval or tailed,
irregularly shaped, aud sometimes very pale ; while numerous cells containing
blood-corpuscles are found in the marrow of bone (Riess). Curiously enough in
this disease, although the red blood-corpuscles are diminished in number, some
may be larger and contain more hemoglobin than do normal corpuscles (Laache).
The number of coloured corpuscles is also diminished in chronic poisoning by lead
or miasmata, and also by the poison of syphilis.

(3.) Abnormal forms of the red corpuscles have been observe! after severe
bums (Lesser) ; the corpuscles are much smaller, and under the influence of the
heat, particles seem to be detached from them just as can be seen happening under
the microscope as the effect of heat (Wertheim). Disintegration of the, corpuscles
into fine droplets has been observed in various diseases, as in severe malarial
fevers. The dark granules of a pigment closely related to haeinatin are derived from
the granules arising from the disintegration of the blood-corpuscles, and these
particles float in the blood (Melancemia). They are partly absorbed by the colour-
less corpuscles, but they are also deposited in the spleen, liver, brain, and bone-
marrow (Arnstein). Sometimes the red corpuscles are abnormally soft, and
readily yield to pressure.

The white corpuscles are enormously increased in number in Leukaemia
(J. H. Bennett and Virchow) ; sometimes even to the extent of the red corpuscles.
In some cases the blood looks as if it were mixed with milk. The colourless cor-
puscles seem to be formed chiefly in bone-marrow (Neumann), but also in the
spleen and lymphatic glands.

11. Chemical Constituents of the Red
Blood-Corpuscles.

(1.) The colouring-matter or haemoglobin (Hb) (Hsemato-globulin,
Heemato-crystaUin) is the cause of the red colour of blood ; it also occurs

24

PREPARATION OF H/EMOGLOBIN CRYSTALS.

in muscle, and in traces in the fluid part of blood, but in this last case
only as the result of the solution of some red corpuscles. Its per-
centage composition is : C 53'85, H 7'32, N 16-17, Fe 0'42, S 0'39,
21 '84 (dog). Its rational formula is unknown, but Preyer gives
the empirical formula C 600 , H 960 , N 154 , Fe, S 3 , 179 . Although it is a
colloid substance it crystallises (Hunefeld 1840, Beichert) in all classes
of vertebrates, according to the rhombic system, and chiefly in rhombic
plates or prisms ; in the guinea-pig in rhombic tetrahedra (v. Lang) ;
in the squirrel, however, it yields hexagonal plates. The varying
forms, perhaps, correspond to slight differences in the chemical com-
position in different cases.

Crystals separate from the blood of all classes of vertebrata during
the slow evaporation of lake-coloured blood, but with varying facility.

The colouring-matter crystallises very readily from the blood of man, dog,
mouse, guinea-pig, rat, cat, hedgehog, horse, rabbit, birds, fishes ; with difficulty
from that of the sheep, ox, and pig. Coloured crystals are not obtained from the
blood of the frog. More rarely a crystal is formed from a single corpuscle
enclosing the stroma. Crystals have been found near the nucleus of the large
corpuscles of fishes, and in this class of vertebrates colourless crystals have been
observed.

Haemoglobin crystals are doubli/
refractive and pleo-chromatic ; they
are bluish-red with transmitted light,
scarlet-red by reflected light. They
contain from 3 to 9 per cent, water
of crystallisation, and are soluble in
water, but more so in dilute alkalies.
They are insoluble in alcohol, ether,
chloroform, and fats. The solutions
are dichroic ; red in reflected light,

and green in transmitted light,

In the act of crystallisation' the. haemoglobin
seems to undergo some internal change.
Before it crystallises it does not diffuse like
a true colloid, and it also rapidly decomposes
hydric peroxide. If it be redissolved after
i f , crystallisation it diffuses, although only to

i < '^_ i > 1 1 1 i ^ > i L>ii i j 1 1 , L). It (nil 1*1 i i

, iii f ,1 a small extent, but it no longer decomposes

human blood ; c, from the cat ; , , . , f . , , .,

-. ,. , , . . nvdric peroxide, and is decolourised by it.

d, from the guinea-pig; e, /, , 1 ,., ,, -.1.- v

, f ^ -i A body like an acid is deposited from ha?mo-

hamster; f, squirrel. . J . 1*1

globm at the positive pole of a battery.

Fig. 8.
Haemoglobin crystals

12, Preparation of Haemoglobin Crystals.

Method Of Rollett. Place defibrinated blood in a platinum capsule, allow
the capsule and the blood to freeze by setting them in a freezing-mixture, and

ESTIMATION OF H.KMOGLOBlN. L>5

then gradually to thaw ; pom- the lake-coloured blood into a plate, until it
forms a stratum not more than 1| in. in. in thickness, and allow it to evaporate
slowly in a cool place, when crystals will separate.

Method of Hoppe-Seyler. Mix defibrinated blood with ten volumes of a 20
per cent, salt solution, and allow it to stand for two days. Remove the clear
upper fluid with a pipette, wash the thick deposit of blood-corpuscles with
water, and afterwards shake it for a long time with an equal volume of ether,
which dissolves the blood-corpuscles. Remove the ether, filter the lake-coloured
blood, add to it | of its volume of cold (0) alcohol, and allow the mixture
to stand in the cold for several days. The numerous crystals can be collected in
a filter and pressed between folds of blotting-paper.

Method of Gscheidlen. Crystals several centimetres in length were obtained
by taking defibrinated blood which had been exposed for twenty-four hours to the
air, aud keeping it in a closed tube of narrow calibre for several days at 37C.
When the blood is spread on glass, the crystals form rapidly. [Vaccine tubes
answer very well.]

[Method of Stirling and Brito- It is in many cases sufficient to mix a drop
of blood with a few drops of water on a microscopic slide, and to seal up the
preparation. After a few days beautiful crystals are developed. The addition of
water to the blood of some animals, such as the rat aud guinea-pig, is rapidly
followed by the formation of crystals of haemoglobin. Very lai'ge crystals may
be obtained from the stomach of the leech several days after it has sucked blood.]

13. Quantitative Estimation of HsemogloMn*

(a.) From the Amount Of Iron- As dry (100 C C.) haemoglobin contains 0'42
per cent, of iron, the amount of iron may be calculated from the amount of
haemoglobin. If m represents the percentage amount of metallic iron, then the
percentage of haemoglobin in blood is

100m
: 0-42

The procedure is the following: Calcine a weighed quantity of blood, and exhaust
the ash with HC1 to obtain ferric chloride, which is transformed into ferrous
chloride. The solution is then titrated with potassic permanganate.

(b.) Colorimetric Method. Prepare a dilute watery solution of haemoglobin
crystals of a known strength. With this compare an aqueous dilution of the
blood to be investigated, by adding water to it until the colour of the test
solution is obtained. Of course, the solutions must be compared in vessels with
parallel sides and of exactly the same width, so as to give the same thickness of
fluid (Hoppe-Seyler). [In the vessel with parallel sides, or, h&matinometer, the sides
are exactly one centimetre apart. Instead of using a standard solution of oxyhw-
moglobiii, a solution of picro-carminate of ammonia may be used (Rajewsky,
Malassez. ) ]

(c.) By the Spectroscope- Preyer found that a O'S per cent, watery solution
(1 c.m. thick), allowed the red, the yellow, and the first strip of green to be seen
(Fig. 11, 1). Take the blood to be investigated (about O'S c.m.), and dilute it with
water until it shows exactly the same optical effects in the spectroscope. If A- is
the percentage of Hb, which allows green to pass through (O'S per cent.), b, the
volume of blood investigated (about 0'5 c.m.), -w, the necessary amount of water
added to dilute it, then x the percentage of Hb in the blood to be investi-
gated

k (w + 1)
I,

26

THE H/EMOGLOBINOMETER.

[ (d.) The Hsemoglobinometer of Gowers is used for the clinical estimation of
luemoglobin.]

" The tint of the dilution of a given volume of blood with distilled water is
taken as the index of the amount of haemoglobin. The distilled water rapidly
dissolves out all the haemoglobin, as is shown by the fact that the tint of the
dilution undergoes no change on standing. The colour of a dilution of average
normal blood one hundred times is taken as the standard. The quantity of
haemoglobin is indicated by the amount of distilled water needed to obtain the
tint with the same volume of blood under examination as was taken of the
standard. On account of the instability of a standard dilution of blood, tinted
glycerine-jelly is employed instead. This is perfectly stable, and by means of
carmine and picrooariuiue the exact tint of diluted blood can be obtained.

The apparatus consists of two glass tubes of exactly the same size. One contains
(D) a standard of the tint of a dilution of 20 cubic m.m. of blood, in 2 cubic centi-
metres of water (1 in 100).

The second tube (C) is graduated, 100 degrees = two centimetres (100 times
twenty cubic millimetres).

The twenty cubic millimetres of blood are measured by a capillary pipette (B)
(similar to, but larger than that used for the haemacytoineter). This quantity of
the blood to be tested is ejected into the bottom of the tube, a few drops of distilled
water being first placed in the latter. The mixture is rapidly agitated to prevent
the coagulation of the blood. The distilled water is then added drop by drop
(from the pipette stopper of a bottle [A] supplied for that purpose) until the tint of
the dilution is the same as that of the standard, and the amount of water which has
been added (i.e., the degree of dilution) indicates the amount of haemoglobin.

Since average normal blood yields the tint of the standard at 100 degrees of
dilution, the number of degrees of dilution necessary to obtain the same tint with

a given specimen of blood
is the pei'centage propor-
tion of the haemoglobin
contained in it, compared
to the normal.

For instance, the 20
cubic millimetres of
blood from a patient
with anaemia gave the
standard tint at 30
degrees of dilution.
Hence it contained only
30 per cent, of the normal
quantity of haemoglobin.
By ascertaining with the
haemacytometer the cor-
puscular richness of the
blood, we are able to
compare the two. A
fraction, of which the
numerator is the per-

r.

Fig. 9.

A, pipette bottle for distilled water; B, capillary pipette; centage of haemoglobin,
C, graduated tube ; D, tube with standard dilution ; antl tbe denominator
F, lancet for pricking the finger. the Percentage of cor-

puscles, gives at once

the average value per corpuscle. Thus the blood mentioned above containing 30
pei- cent, of haemoglobin, contained GO per cent, of corpuscles ; hence the average

USE OF THE SPECTROSCOPE. 27

value of each corpuscle was %% or of the normal. Variations in the amount of
haemoglobin may be recorded on the same chart as that employed for the corpuscles.

In using the instrument, the tint may be estimated by holding the tubes between
the eye and the window, or by placing a piece of white paper behind the tubes ;
the former is perhaps the best. Care must be taken that the tubes are always
held in the line of light, not below it. In the latter case some light is reflected
from the suspended corpuscles from which the haemoglobin has been dissolved.
If the value of the corpuscles is small, then a perceptibly paler tint is seen when
the tubes are held below the line of illumination. If all the light is transmitted
directly through the tubes, the corpuscles do not interfere with the tint.

In using the instrument it will be found that, during 6 or 8 degrees of dilution,
it is difficult to distinguish a difference between the tint of the tubes. It is there-
fore necessary to note the degree at which the colour of the dilution ceases to be
deeper than the standard, and also that at which it is distinctly paler. The degree
midway between these two will represent the haemoglobin percentage.

The instrument is only expected to yield approximate results, accurate within
2 or 3 per cent. It has, however, been found of much iitility in clinical observa-
tion."]

The amount of haemoglobin in man is 12 to 15 per cent., in the
woman 12 to 14 per cent., during pregnancy 9 to 12 per cent.
(Preyer). According to Leichtenstern, Hb is in greatest amount in
the blood of the newly-born infant, but after ten weeks the excess
disappears. Between six months and five years, it becomes least in
amount, reaches its second highest maximum between twenty-one
and forty-five, and then sinks again. From the tenth year onwards
the blood of the female is poorer in Hb. The taking of food causes a
temporary decrease of the Hb, owing to the dilution of the blood.

Pathological- A decrease is observable during recovery from febrile condi-
tions, and also during phthisis, cancer, ulcer of the stomach, cardiac disease,
chronic diseases, chlorosis, leuktemia, pernicious antemia, and during the rapid
mercurial treatment of syphilitic persons.

14. Use of the Spectroscope.

As the spectroscope is frequently used in the investigation of blood and other
substances of the body, it will be convenient to give a short description of the
instrument here (Fig. 10). It consists of (1. ) a tube, A, which has at its peripheral
end a slit, S (that can be narrowed or widened). At the other end a collecting l< ns,
C (called a collunator) is placed, so that its focus is in exact line with the slit.
Light (from the sun or a lamp) passes through the slit, and thus goes parallel
through C to (2.) the prism, P, which decomposes the parallel rays into a
coloured spectrum, r - r. (3. ) An astronomical telescope is directed to the spectrum,
r - v, and the observer, B, with the aid of the telescope, sees the spectrum magnified
from six to eight times ; (4.) a third tube, D, contains a delicate scale, M, on glass,
whose image, when illuminated, is reflected from the prism to the eye of the
observer, so that he sees the spectrum, and over or above it the scale. To keep
out other rays of light the inner ends of the three tubes are covered by metal or
by a dark cloth (see also Blood in urine).

[The micro-spectroscope, e.g., that known as the ' Sorby-Browuiug " micro-
spectroscope is very useful when small quantities of a solution are to be examined.]

ABSORPTION AND FLAME SPECTRA.

[Every spectroscope ought to give two spectra, so that the position of any absorp-
tion baud may be definitely ascertained. The spectroscope is fitted into the
ocular end of the tube of a microscope instead of the eye-piece. Small cells for
containing the fluid to be examined are made from short pieces of barometer-tubes
cemented to a plate of glass.]

B

Fig. 10.

Scheme of a spectroscope for observing the spectrum of blood A, tube ; >S, slit ;
m m, layer of blood with flame in front of it ; P, prism ; M, scale ; B, eye of
observer looking through a telescope ; r r, spectrum.

Absorption Spectra. If a coloured medium (e.g., a solution of blood)
be placed between the slit and a source of light, all the rays of coloured
light do not pass through it some are absorbed ; many yellow rays are
absorbed by blood, hence that part of the spectrum appears dark to
the observer. On account of this absorption, such a spectrum is called
an "absorption spectrum"

Flame Spectra. If mineral substances be burned on a platinum-
wire in a non-luminous flame (Bunsen's burner) in front of the slit, the
elements present in the mineral or ash give special coloured band or
bands, which have a definite position. Sodium gives a yellow,
potassium a red and a violet line. These substances are found in
burning the ashes of almost all organs.

If sunlight be allowed to fall upon the slit, the spectrum shows
a large number of lines (Fraunhofer's lines) which occupy definite posi-
tions in the coloured spectrum. These lines are indicated by the
letters A, B, C, D, etc., a, b, c, etc. (Fig. 11).

COMPOUNDS OF HAEMOGLOBIN.

29

15, Compounds of Haemoglobin with 0; Oxytomoglobin,

and Mettomoglobin.

(1.) Oxyhasmoglobin (0 Hb) behaves as a weak acid, and occurs to
the extent of 8678 to 94'30 per cent, in dry red human corpuscles
(Jiidell). It is formed very readily whenever Hb comes into
contact with or atmospheric air. 1 gramme Hb unites with
1-6 to 1'8 cubic centimetres of at and 760 mm. Hg pressure.
Oxyhaemoglobin is a very loose chemical compound, and is slightly less
soluble than Hb ; its spectrum shows in the yellow and the green, two
dark absorption-bands (Hoppe-Seyler) whose length and breadth in a
0'18 per cent, solution are given in Fig. 11 (2).

Yellow.

Green.

Blue.

Red. Orange.

Illl ILIUIU I II.LI ILLI Ullllililllll

5o bo 70 80 oo 100 tio

A a B C

o =

Eaiiiofrlobin

0,8 7,

O =

Hemoglobin
0-18 7,

Ca rbonic

Oxide
Hamoglobin.

Reduced
Hamoglobin.

Hamatin in

Alcohol, with

Sulphuric

Acid.

Hamatin in

an Alkaline

Solution.

Reduced
Hamatin.

Various spectra of haemoglobin and its compounds.

30 REDUCTION OF HAEMOGLOBIN.

[The two absorption-bands lie between the lines D and E, the band
nearer D being more sharply defined and narrower than the second
band, which is wider and less clearly marked-off, and lies nearer E.]

It occurs in the blood-corpuscles, circulating in arteries and capillaries,
as was shown by the spectroscopic examination of the ear of a rabbit, of
the prepuce and the Aveb of the fingers (Vierordt).

Reduction of Oxyhsemoglobin. It gives up its very readily, how-
ever, even when means which set free absorbed gases are used. It is
reduced by the removal of the gases by the air-pump, by the conduction
through its solution of other gases (CO & NO), and by heating to the
boiling point. In the circulating blood its is very rapidly given up
to the tissues, so that in suffocated animals only reduced hcemoglobin
is found in the arteries. Some constituents of the serum and sugar
use up 0. By adding to a solution of oxyhsemoglobin reducing sub-
stances e.g., ammonium sulphide, ammoniated tartarate of zinc oxide
solution, iron filings, or Stokes's fluid [tartaric acid, iron proto-sulphate,
and excess of ammonia] the two absorption bands of the spectrum dis-
appear, and reduced hemoglobin (gas-free) (Fig. 11, 4), with one absorp-
tion band is formed (Stokes, 18G4). [The single band which is obtained
from reduced haemoglobin lies between D and E, and its most deeply
shaded portion is opposite the interval between the two bands of oxy-
hsemoglobin. Its edges are less sharply defined. The colour of the
blood changes from a bright red to a brownish tint. Hoppe-Seyler
applies the term Haemoglobin to the reduced substance to distinguish it
from oxyhwmoglobin.]

The two bands are reproduced by shaking the reduced haemoglobin
with air, whereby O Hb is again formed. Solutions of oxyhajmoglobin
are readily distinguished by their scarlet colour from the purplish tint
of reduced hemoglobin.

If a string be tied round the base of two fingers so as to interrupt the circulation,
the spectroscopic examination shows that the oxyhffimoglobin rapidly passes into
reduced Hb (Vierordt). Cold delays this reduction (Filehne).

The spectroscopic examination of small blood-stains is often of the utmost
forensic importance. A minimal drop is sufficient. Dissolve in a few drops of
distilled water, and place in a thin glass tube in front of the slit of the spectroscope.

(2.) Methsemoglobin (Hoppe-Seyler) contains more than oxy-
hsemoglobin (Fig. 11, 5). Chemically it is fairly stable, contains 0, and
crystallises (Hiifner and J. Ott). It is obtained by acting upon a
solution of reduced or oxyhtemoglobin with oxidising reagents ; best,
however, by adding crystals of potassic ferridcyanide. It shows four
absorption bands like an acid solution of heematin, that between C and
D being the only one sharply defined.

If a trace of ammonia be added to such a solution, it gives an alkaline solution
of methsemoglobin, which shows two bands like oxyhajmoglobin, of which the first

CARBONIC OXIDE-HEMOGLOBIN. 31

one ia the broader, and extends more into the red. If ammonium sulphide be
added to the methaemoglobin solution, reduced Hb is formed (Jiiderholm). Methae-
raoglobin is produced in old brown blood-stains, in the crusts of bloody wounds, in
blood cysts farther by the addition of minute traces of acid to blood, or by
heating blood with a trace of alkali. Sorby and Jaderholm regard it as a per-
oxidised haemoglobin, but this view is opposed by Hoppe-Seyler. It may also
be prepared by acting upon blood with potassic chlorate and nitrate, or nitrate of
amyl, which gives to blood a chocolate-brown colour (Saarbach, Gamgee).

16. Carbonic Oxide-Haemoglobin.

(3.) CO-Hsemoglobin is a more stable chemical compound than the
foregoing, and is produced at once when carbonic oxide is brought into
contact with pure Hb or 2 Hb (Cl. Bernard, 1857). It has an
intensely florid or cherry-red colour, and gives two absorption-bands,
very like those of 2 Hb, but they are slightly closer together and lie
more towards the violet (Fig. 11, 3). Reducing substances (which act
upon Hb0 ) do not affect these bands, i.e., they cannot convert the CO
compound into reduced Hb. Another good test to distinguish it from
Hb0 2 is the soda test. If a 10 per cent, solution of caustic soda be
added to a solution of CO-Hb, and heated, it gives a cinnabar-red colour;
while, with an Hb0 2 solution, it gives a dark-brown, greenish, greasy
mass (Hoppe-Seyler). Oxidising substances [solutions of potassic
permanganate (O025 per cent.), potassic chlorate (5 per cent.), and
dilute chlorine solution] make solutions of CO-Hb, cherry-red in
colour, while they turn solutions of HbO., pale yellow. After this
treatment both solutions show the absorption-bands of methaemoglobin.
If ammonium sulphide be added, Hb0 2 and CO-Hb are re-formed.

On account of its stability CO-Hb resists external influences and even putre-
faction for a long time (Hoppe-Seyler), and the two bands of the spectrum may be
visible after many months. Landois obtained the soda test and spectroscopic
bands in the blood of a woman poisoned 18 months previously by CO, and after
great putrefaction of the body had taken place.

If CO is breathed by man, or if air containing it be inspired, it
gradually displaces the 0, volume for volume, out of the Hb (L. Meyer),
and death soon occurs; 1,000 ccm inspired at once will kill a man.
A very small quantity in the air (^^"T^V o) suffices, in a relatively
short time, to form a large quantity of CO-Hb (Grehant). As
continued contact with other gases (such as the passing of through
it for a very long time) gradually separates the CO from the Hb
(with the formation of 2 Hb Donders), it happens that, in very partial
poisoning with CO, the blood gradually gets rid of the latter. A
high degree of poisoning necessitates the transfusion of blood (p. 61).

[Gamgee and Zuntz also find that although the CO-Hb compound is very stable,
yet it may be reduced by passing air or neutral gases through, it for a lengthened
period ; it is also reduced when blood is boiled in the mercurial pump. ]

32 POISONING BY CARBONIC OXIDE.

17. Phenomena of Poisoning by Carbonic Oxide. Other
Compounds of Haemoglobin.

Carbonic oxide is formed during incomplete combustion of coal or coke, and
passes into the air of the room, provided there is not a free outlet for the
products of combustion. It occurs to the extent of 12-28 per cent, in ordinary
gas, which largely owes its poisonous properties to the presence of CO. If the
be gradually displaced from the blood by the respiration of air containing CO, life
can only be maintained as long as sufficient can be obtained from the blood to
support the oxidations necessary for life. Death occurs befoi-e all the is dis-
placed from the blood. CO has no effect when directly applied to muscle and
nerve. When it is inhaled, there is first stimulation and afterwards paralysis of
the nervous system, as shown by the symptoms induced, e.g., violent headache,
great restlessness, excitement, increased activity of the heart and respiration,
salivation, tremors, and spasms. Later, unconsciousness, weakness, and paralysis
occur, laboured respiration, diminished heart-beat, and lastly, complete loss of
sensibility, cessation of the respiration and heart-beat, and death. At first
the temperature rises several tenths of a degree, but it soon falls 1 or more. The
pulse is also increased at first, but afterwards it becomes very small and frequent.

In poisoning with pure CO there is 110 dyspnoea, but sometimes muscular spasms
occur, the coma not being very marked. There is also temporary but pronounced
paralysis of the limbs, followed by violent spasms. After death the heart and
brain are congested with intensely florid blood. lu poisoning with the vapour of
charcoal, where CO and C0 2 both occur, there is a varying degree of coma ; pro-
nounced dyspnrea, muscular spasms which may last several minutes, gradual
paralysis and asphyxia, moniliform contractions and subsequent dilatation of the
blood-vessels, with congestion of various organs, occur, accompanied by a fall of the
blood-pressure (Klebs), indicating initial stimulation and subsequent paralysis of
the vaso-motor centre. This also explains the variations in the temperature and
the occasional occurrence of sugar in the urine after poisoning with CO. After
death, the blood-vessels are found to be filled with fluid blood of an exquisitely
bright cherry-red colour, while all the muscles and viscera and exposed parts of
the body (such as the lips) have the same colour. The brain is soft and friable,
there are catarrh of the respiratory organs and degeneration of the muscles, and
great congestion and degeneration of the liver, kidneys, and spleen. The spots of
lividity, post-mortem, are bright red. After recovery from poisoning with CO,
there may be paraplegia and (although more rarely) disturbances of the cerebral
activity. The poisonous action of the vapours of combustion was known to
Aristotle.

(4.) Nitric Oxide -Haemoglobin (NO-Hb) is formed when NO is
brought into contact with Hb (L. Hermann).

As NO has a great affinity for 0, red fumes of nitrogen peroxide (NOo) being
formed whenever the two gases meet, it is clear that, in order to prepare NO-Hb,
the O must first be removed. This may be done by passing H through it, [or
ammonia may be added to the blood, and a stream of NO passed through it ; the
ammonia combines with all the acid formed by the union of the NO with the
O of the blood]. NO-Hb is a more stable chemical compound than CO-Hb,
which, as we have seen, is again more stable than OjHb. It has a bluish-violet
tint, and also gives two absorption -bands in the spectrum similar to those of the
other two compounds, but not so intense. These bands are not abolished by the
action of reducing agents.

The three compounds of Hb, with 0, CO, and NO, are crystalline;
like Hb, they are isomorphous, and their solutions are not dichroic. One

DECOMPOSITION OF HEMOGLOBIN. 33

gramme Hb unites with 1 '33-1 '35 e.c.rn. of each of the gases at
and 1 metre pressure (Preyer, L. Hermann).

(5.) Cyanogen, CNH (Hoppe-Seyler), and acetylene, C 2 H 2 (Bistrow and
Liebreich), form easily decomposable compounds with Hb. The former occurs in
poisoning with hydrocyanic acid, and has a spectrum identical with that of 2 Hb,
and, like 2 Hb, it is reduced by special agents. [The existence of these com-
pounds is, however, highly doubtful (Gamgee).]

(6.) If C0 3 be passed through a solution of oxyhaemoglobin for a con-
siderable time, reduced Hb is first formed ; but if the process be
prolonged the HI) is decomposed, a precipitate of globulin is thrown
down, and an absorption-band, similar to that obtained when Hb is
decomposed with acids, is observed (see p. 33).

18. Decomposition of Haemoglobin.

In solution and in the dry state Hb gradually becomes decomposed, whereby
the iron -con tain ing pigment hsematin, along with certain bye-products, formic,
lactic, and butyric acids are formed.

Hcemoglobin, however, may be decomposed at once into (1) a body
containing iron ha>matin, and (2) a colourless proteid closely related to
globulin ; by (a.) the addition of all acids, even by C0 2 in the presence
of plenty of water ; (b.) strong alkalies ; (c.) all reagents which coagulate
albumin, and by heat at 70-80C. ; (f/.) by ozone.

(A.) H.EMATIN (C 68 , H 70 , N 8 , Fe,, 10 ) forms about 4 per cent, of haemo-
globin (dog). It is insoluble in water, alcohol, and ether; soluble in
dilute alkalies and acids, and in acidulated ether and alcohol.

When Hb containing is decomposed, haamatin is formed at once ; while Hb
free from on being decomposed forms first a purplish-red body, HVEMOCHROMOGEN
(C 3 4, H 3C , N 4 , Fe 5 ), which contains less 0, and is a precursor of hrematin. In
the presence of it becomes oxidised, and passes into hsematin. In solution it
gives the spectrum shown in Fig. 11, 7 (Hoppe-Seyler). Dilute acids in an
alkaline solution deprive hasmochromogen of its iron, and HJEMATO-POKPHYRIN, a
substance which remains stable in contact with air, is produced. It may also be
produced from hsematin by the action of acids, so that ha?matin is an oxidation
stage of hremochromogen.

(a) Hrpmatin in acid solution. Lecanu extracted it from dry blood-corpuscles
by using alcohol containing sulphuric and tartaric acids. If acetic acid be added
to a solution of Hb, a mahogany-brown fluid is obtained, containing h(f matin in acul
solution, which gives a spectrum with four absorption-bands in the yellow and
green (Fig. 11, 5).

(/3) If this solution be treated with excess of ammonia, Juemalin in alkaline solu-
tion is formed, which gives one absorption-band on the boundary line between red
and yellow (Fig. 11, 6).

(y) Reducing agents cause this band to disappear, and produce in the yellow
two broad bands, which are due to the presence of "reduced hcematin " (Fig.
H, 7).

(<5) When haemoglobin is extravasated into the subcutaneous tissue, it becomes
BO altered that ultimately hydrated oxide of iron appears in its place.

3

34 H^EMIN AND BLOOD TESTS.

19. Hsemin and Blood Tests.

In 1853 Teichmann prepared crystals from blood, which Hoppe-
Seyler showed to be chloride of hcematin or hydrochlorate of hsematin.
The presence of these crystals is nsed as a test for blood-stains or
blood in solution. These crystals of hremin (Fig. 12) are prepared by
adding a small crystal of common salt to dry blood on a glass slide,
and then an excess of glacial acetic acid ; the whole is gently heated
until bubbles of gas are given off. On allowing the preparation to
cool, the characteristic hremin crystals are obtained (Hrematin, + 2HC1).

Characters. When well-formed, the crystals are small microscopic
rhombic plates, or rhombic rods; sometimes they are single at other times
they are aggregated in groups, often crossing each other. Some kinds
of blood (ox and pig) yield very irregular, scarcely crystalline, masses.
The crystalline forms of hremin are identical in all the different kinds
of blood that have been examined (Jahnke, Hogyes). They are doubli/
refractive and plco-cliromatic ; by transmitted light they are mahogany-
brown, and by reflected light bluish-black, glancing like steel. They
give a brown streak on porcelain.

(1.) Preparation from Dry Blood-Stains. Place a few particles
of the blood-stain on a glass slide, add 2 to 3 drops of glacial acetic
acid and a small crystal of common salt; cover with a cover-glass,
and heat gently over the flame of a spirit-lamp until bubbles of gas
are given off. On cooling, the crystals appear in the preparation
(Fig. 13).

^ v V , v
~ ,* ^ * v V / *

_ \

Fig. 12. Fig. 13.

Hnemin Crystals of various forms. Hsemin Crystals prepared from

traces of blood.

(2.) From Stains on Porous Bodies. The stained object (cloth,
wood, blotting-paper, earth) is extracted with a small quantity of dilute
caustic potash, and afterwards with water in a watch-glass. Both
solutions are carefully filtered, and tannic acid and glacial acetic acid
are added until an acid reaction is obtained. The dark precipitate
which is formed is collected on a filter and washed. A small part of

JLEMIN AND BLOOD TESTS. 35

it is placed on a microscope slide, a granule of common salt is added,
and the whole dried ; the dry stain is treated as in ( 1 .) (Struwe).

(3.) From Fluid Blood. Dry the blood slowly at a low temperature,
and proceed as in (1.)

(4.) From very Dilute Solutions of Haemoglobin. (.) Strmve's
Method Add to the fluid, ammonia, tannic acid, and afterwards glacial
acetic acid, until it is acid; soon a black precipitate of tannate of
hrematin is thrown down. This is isolated, washed, dried, and treated
as in (1.), but instead of Nad a granule of ammonium chloride is added.

(b.) Guning and van Geuns recommend the addition of zinc acetate, which gives
a reddish precipitate; this precipitate is to he treated as in (1.)

Hpemin crystals may sometimes be prepared from putrefying or
lake-coloured blood, but they are very small, and here the test often
fails. When mixed with iron-rust, as on iron-weapons, the blood-
crystals are generally not formed. In such cases, scrape off the stains
and boil them with dilute caustic potash. If blood be present, the
dissolved hsematiy forms a fluid, which in a thin layer is green ; in a
thick layer red (H. Rose).

Chemical Characters. Hcemiii crystals have been prepared from all classes of
vertebrates and from the blood of the earth-worm.

They are insoluble in water, alcohol, ether, chloroform ; but HoSC^ dissolves
them, expelling the HC1, and giving a violet-red colour. Ammonia also dissolves
them, and if the resulting solution be evaporated, heated to 130C., and treated
with boiling water (which extracts the ammonium chloride), pure hcematin is
obtained (Hoppe-Seyler) as a bluish-black substance, which on being pounded forms
a brown and amorphous powder. Its solutions in caustic alkalies are dichroic; in
reflected light, brownish-red; in transmitted light, in a thick stratum, red in a
thin one, olive-green. The acid solutions are monochromatic and brown.

An alcoholic solution of ha?matin, when reduced by tin and hydro-
chloric acid, yields urdbilin (Hoppe-Seyler), (compare Bile).

20. Hsematoidin.

Virchow discovered this important derivative from haemoglobin. It
occurs in the body wherever blood stagnates outside the circulation, and
becomes decomposed as when blood is extravasated into the tissues
e.g., the brain in solidified blood-plugs (thrombus) ; invariably in the
Graafian follicles. It contains no iron (C 32 , H 36 , N 4 , 6 ), and crystallises
in clinorhombic prisms (Fig. 14) of a
yellowish-brown colour. It is soluble in
warm alkalies, carbon disulphide, benzol, and
chloroform. Very probably it is identical with
one of the bile pigments bili-rubin (Valen-
teiner). [When acted upon by impure nitric l[^
acid (Gmelin's reaction), it gives the same F - 14

play of colours as bile.] Hfematoidlii Crystals.

36 OTHER CONSTITUENTS OF RED CORPUSCLES.

In cases where a large amount of blood has undergone solution
within the blood-vessels (as by injecting foreign blood), hsematoidin
crystals have been found in the urine (v. Recklinghausen, Landois).

21. (B.) The Colourless Proteid of Haemoglobin.

It is closely related to globulin ; but, while the latter is precipitated
by all acids, even by CO.,, and re-dissolved on passing through it,
the proteid of haemoglobin, on the other hand, is not dissolved after
precipitation on passing through it a stream of 0.

As crystals of haemoglobin can be decolourised under special circumstances, it
is probable that these owe their crystalline form to the proteid which they
contain. Landois placed crystals of haemoglobin along with alcohol in a dialyser,
putting ether acidulated with sulphuric acid outside, and thereby obtained
colourless crystals. [If frog's blood be sealed up on a microscopic slide, along
with a few drops of water for several days, long colourless acicular crystals are
developed in it (Stirling and Brito).]

. 22. II. Proteids of the Stroma.

Dry red human blood-corpuscles contain from 5'10-12'24 per cent.
of these proteids, but little is known about them (Jiidell). One of
them is globulin, which is combined with a body resembling nuclein
(Wooldridge), and traces of a diastatic ferment (v. Wittich). The
stroma tends to form masses which resemble fibrin (Landois).

L. Brunton found a body resembling mucin in the nuclei of red blood- corpuscles,
and Miescher detected nuclein.

23. The Other Constituents of Red Blood- Corpuscles.

III. LECITHIN (0-35-072 per cent.) in dry blood-corpuscles (Jiidell),
and also in brain, yelk, and seminal fluid.

It is regarded as a glycero-phosphate of neurin, in which, in the radical of
glycero-phosphoric acid, two atoms of H are replaced by two of the radical of
stearic acid. By gentle heat glycero-phosphoric acid is split up into glycerine and
phosphoric acid.

CHOLESTERIN (0*25 per cent.); no FATS.

These substances are obtained by extracting stromata or blood itself with ether.
When the ether evaporates, the characteristic globular forms ("myelin-forms ") of
lecithin and crystals of cholesterin are recognised. The amount of lecithin may
be determined from the amount of phosphorus in the ethereal extract.

IV. WATER (681-63 per 1,000 C. Schmidt).

V. SALTS (7-28 per 1,000, C. Schmidt), chiefly compounds of

ANALYSIS OF BLOOD. 37

potash and phosphoric add; the phosphoric acid is derived only from
the burned lecithin ; while the greater part of the sulphuric acid in
the analysis is derived from the burning of the haemoglobin.

Analysis Of Blood. 1 : 000 parts, by weight, of HORSE'S BLOOD contain :

344'IS blood-corpuscles (containing about 128 per cent, of solids).
655'82 plasma (containing about 10 per cent, of solids).

1,000 parts, by weight, of MOIST BLOOD-CORPUSCLES contain:

Solids, 367 '9 (pig); 400'1 (ox).
Water, 632 -1 599 '9

The solids are:

Pig. Ox.

Haemoglobin, . . . . 261' 280 '5

Albumin, 86 '1 107

Lecithin, Cholesterin, and other/ ,<,. ...

Organic Bodies, . . . \

Inorganic Salts, . . . . 8 "9 4'S

{POTASH, . . 5-543 0'747

Magnesia, . . O'lSS O'OIT

Chlorine, . . 1'504 1-635

PHOSPHORIC ACID, 2-067 0'703

Soda, ... 2-093 (Bunge).

24. Chemical Composition of the Colourless

Corpuscles.

Investigations have been made on pus cells, which closely resemble
colourless blood-corpuscles. They contain several proteids ; alkali albu-
ininate, a proteid which coagulates at 48C., and another resembling
myosin, fibrino-plastin, and a coagulating ferment; nuclein in the
nuclei (Miescher); perhaps also glycogen (Salomon), lecithin, and
extractives.

100 parts, by weight, of dry PUS contain:

Earthy Phosphates, . . 0'416
Sodic Phosphate, . 0'606

Potash, . . . 0-201

Sodic Chloride, . . . 0'143

25. Blood-Plasma and its Relation to Serum.

The unaltered fluid in which the blood-corpuscles float is called plasma,
or liquor sangulnit. This fluid, however, after blood is withdrawn from the
vessels, rapidly undergoes a change, owing to the formation of a solid
fibrous substance, FIBRIN, which seems to be produced by the coming
together of three special substances, the so-called fibrin-factors. After this
occurs, the new fluid which remains no longer coagulates spontaneously
(it is plasma, minus the fibrin-factors), and is called scrum. Apart from

38 PREPARATION OF PLASMA.

the presence of the fibrin-factors, the chemical composition of plasma
and serum is the same.

[When blood coagulates, the following rearrangement of its elements takes
place :

BLOOD.

Plasma. Corpuscles, \ re , :,

. j white.

A __

I I

feerum. Fibrin.

u-

I

Fibrin, Corpuscles, and some Serum (Blood Clot).]

The serum, however, still contains a portion of the fibrin-ferment,
and also some of the fibrino-plastin or fibrino-plastic substance.
Plasma is a clear, transparent, slightly thickish fluid, which, in most
animals (rabbit, ox, cat, dog), is almost colourless; in man it is
yellow, and in the horse citron-yellow.

26. Preparation of Plasma.

(A.) Without Admixture. Taking advantage of the fact that
plasma, when cooled to outside the body, does not coagulate for a
considerable time, Briicke prepares the plasma thus: Selecting the
blood of the horse (because it coagulates slowly, and its corpuscles sink
rapidly to the bottom), he receives it, as it flows from an artery, in a
tall narrow glass, placed in a freezing-mixture, and cooled to 0. The
blood remains fluid, and, the coloured corpuscles subsiding in a few
hours, the plasma remains above as a clear layer, which can be removed
with a cooled pipette. If this plasma be then passed through a cooled
filter, it is robbed of all its colourless corpuscles.

[Burdon-Sanderson uses a vessel consisting of three compartments
the outer and inner contain ice, while the blood of the horse is
caught in the central compartment, which does not exceed half-an-inch
in diameter.]

The quantity of plasma may be roughly (but only roughly) estimated
by using a tall, graduated measuring-glass. If the plasma be warmed,
it soon coagulates (owing to the formation of fibrin), and passes into
a trembling jelly. If, however, it be beaten with a glass-rod, the
fibrin is obtained as a white stringy mass, adhering to the rod. The
quantity of fibrin in a given volume of plasma is about 0'7 1 pel-
cent., although it varies much in different cases.

COAGULATION OF THE BLOOD. 39

(B.) With Admixture. Blood flowing from an artery is caught in a
tall graduated measure containing -1-th of its volume of a concentrated
solution of sodic sulphate (Hewson) or in a 25 per cent, solution of
maguesic sulphate (1 vol. to 4 vols. blood : Semmer) or 1 vol. blood
with 2 vols. of a 4 per cent, solution of monophosphate of potash
(Masia). When the blood is mixed Avith these fluids and put in a
cool place, the corpuscles subside, and the clear stratum of plasma
mixed with the salts may be removed with a pipette. If the salts be
removed by dialysis, coagulation occurs; or it may be caused by the
addition of water (Joh. Miiller). Blood which is mixed with a 4 per
cent, solution of common salt does not coagulate, so that it also may
be used for the preparation of plasma. [For frog's blood Johannes
Miiller used a ^ per cent, solution of cane s,ugar, which permits the
corpuscles to be separated from the plasma by filtration. The plasma
mixed with the sugar coagulates in a short time.]

27. Fibrin Coagulation of the Blood.

General Characters. Fibrin is that substance which, becoming
solid in shed blood, in plasma and in lymph causes coagulation. In
these fluids, when left to themselves, fibrin is formed, consisting of
innumerable, excessively delicate, closely-packed, microscopic, doubly
refractive (Hermann) fibrils (Fig. 6, E). These fibrils entangle the
blood-corpuscles as in a spider's web, and form with them a jelly-like,
solid mass called the BLOOD-CLOT (placenta sanguinis). At first the
clot is very soft, and after the first 2 to 15 minutes a few fibres may be
found on its surface; these may be removed with a needle, while the
interior of the clot is still fluid. The fibres ultimately extend throughout
the entire mass, which, in this stage, has been called cruor. After
from 12 to 15 hours the fibrin contracts, or, at least, shrinks more
and more closely around the corpuscles, and a fairly solid, trembling,
jelly-like clot, which can be cut with a knife, is formed. During this
time the clot has expressed from its substance a fluid the BLOOD-SERUM.
The clot takes the shape of the vessel in which the blood coagulates.
Fibrin may be obtained by washing away the corpuscles from the
clot with a stream of water.

Crusta Phlogistica. If the corpuscles subside very rapidly, and if
the blood coagulates slowly, the upper stratum of the clot is not red,
but only yellowish, on account of the absence of coloured corpuscles.
This is regularly the case in horse's blood, and in human blood it is
observed especially in inflammations ; hence this layer has been called
crusta pliloyistica. Such blood contains more fibrin, and so coagulates
more slowly.

40 PHENOMENA OF COAGULATION.

The crusta is formed under other circumstances, but the cause of its formation
is not always clear e.f/., with increased S.G. of the corpuscles, or diminished S.G.
of the plasma (as in hydrsemia and chlorosis), whereby the corpuscles sink more
rapidly, and also during pregnancy. The taller and narrower the glass, the thicker
is the crusta (compare 41). The upper end of the clot, where there are few
corpuscles, shrinks more, and is therefore smaller than the rest of the clot. This
upper, lighter-coloured layer is called the ' : buffy" coat ; this, however, gradually
passes both as to size and colour into the normal dark-coloured clot. [Sometimes
the upper surface of the clot is concave or cupped. The older physicians used to
attribute great importance to this condition, and also to the occurrence of the
crusta phlogistica, or buffy coat.]

Defibrinated Blood. If freshly-shed blood be beaten or whipped
with a glass-rod or with a bundle of twigs, fibrin is deposited on the
rod or twigs in the form of a solid, fibrous, yellowish-white, elastic-
mass, and the blood which remains is called " defilnnated Hood" [The
twigs and fibrin must be washed in a stream of water to remove
adhering corpuscles.]

Coagulation of Plasma. Plasma shows phenomena exactly analogous,
save that there is no well-defined clot, owing to the absence of the
resisting corpuscles ; there is, however, always a soft, trembling jelly
formed, when plasma coagulates.

Properties of Fibrin. Although the fibrin appears voluminous, it
only occurs to the extent of 0'2 per cent. (O'l to O3 per cent.) in the
blood. The amount varies considerably in two samples of the same
blood (Sig. Mayer). It is insoluble in water and ether; alcohol shrivels
it by extracting water; dilute hydrochloric acid (O'l per cent.) causes
it to swell up and become clear, and changes it into syntonin or acid-
albumin. When fresh, it has a grayish-yellow fibrous appearance, and
is elastic ; when dried, it is horny, transparent, brittle, and friable.

When fresh it dissolves in 6 to 8 per cent, solutions of sodium nitrate or
sulphate, in dilute alkalies, and in ammonia thus forming alkali-albuminate.
Heat does not coagulate these solutions. If, however, to a solution of fibrin in
0'05 per cent, soda solution, there be added acids, or (the faintly alkaline) lactate,
formate, butyrate, acetate, or valerianate of ammonia or soda, coagulation occurs
(Deutschmanu). Hydric peroxide is rapidly decomposed by fibrin (The'nard).

According to H. Nasse, the first appearance of a coagulum occurs in man's
blood after 3 min. 45 sec., in woman's blood after 2 min. 20 sec. Age has no effect;
withdrawal of food accelerates coagulation (H. Vierordt).

28. General Phenomena of Coagulation.

I. Blood which is in direct contact with the living and unaltered
blood-vessels does not coagulate (Briicke, 1857). This important fact
was proved by Briicke, who filled the heart of a tortoise with blood which
had stood 1 5 minutes exposed to the air at 0, and kept it in a moist
chamber. The blood was still fluid at the end of 5^ hours, while the

PHENOMENA OF COAGULATION. 41

heart itself still continued to beat. He observed that at the blood
was uncoagulated in the contracting heart of a tortoise after eight days.
Blood inside a contracting frog's heart preserved under mercury does
not coagulate. If the wall of the vessel be altered by pathological pro-
cesses (e.g., if the intima becomes rough and uneven, or undergoes
inflammatory change) coagulation is apt to occur at these places.
Blood rapidly coagulates in a dead heart, or in blood-vessels (but not
in capillaries) or other canals (e.g., the ureter) (Virchow).

If blood stagnates in a living vessel, coagulation begins in the central
axis, because here there is no contact with the wall of the living blood-
vessel. This influence of the wall of blood-vessels was, to some extent,
known to Thackrah (1819) and to Sir Astley Cooper.

II. Conditions which Hinder or Delay Coagulation. (a.) The
addition of small quantities of alkalies and ammonia, or of con-
centrated solutions of neutral salts of the alkalies and earths (alkaline
chlorides, sulphates, phosphates, nitrates, carbonates). Magnesic
sulphate acts most favourably in delaying coagulation (1 vol. solution
of 28 per cent, to 3^ vol. blood of the horse).

(&.) The precipitation of the fibrinoplastin by adding weak acids, or
by C0 2 .

By the addition of acetic acid until the reaction is acid, the coagulation is com-
pletely arrested. A large amount of C0 2 delays it, and hence venous blood
coagulates more slowly than arterial. Hence, also, the blood of suffocated persona
remains fluid.

(c.) The addition of egg-albumin, syrup, glycerine, and much water.
If uncoagulated blood be brought into contact with a layer of already-
formed fibrin, coagulation occurs later.

(d.) By cold at coagulation may be delayed for one hour
(J. Davy.) If blood is frozen at once, after thawing, it is still fluid,
and then coagulates (Hewson). When shed blood is under high
pressure it coagulates slowly (Landois).

(e.) Blood of embryo-fowls does not coagulate before the 12th or 14th
day of incubation (Boll); that of the hepatic rein very slightly;
menstrual blood shows little tendency to coagulate when alkaline mucus
from the vagina is mixed with it. If it be rapidly discharged, it
coagulates in masses.

(/.) Blood rich in fibrin from inflamed parts coagulates slowly. In "bleeders "
(haemophilia), coagulation seems not to take place, owing to a want of the sub-
stances producing fibrin ; hence, in these cases, wounds of vessels are not plugged
with fibrin. Albertoni observed that if tryptic pancreas ferment (dissolved in
glycerine), be injected into the blood of an animal, blood does not coagulate.
Schmidt-Mulheim found that after the injection of pure peptone into the blood
(0'3 to 0'6 grammes per kilo.) of a dog, the blood lost its power of coagulating.
A substance is formed in the plasma, which prevents coagulation, but which is

42 PHENOMENA OF COAGULATION.

precipitated by C0 2 . Lymph behaves similarly (Fano). After peptones are injected,
there is a great solution of leucocytes in the blood (v. Samson-Himmelstjerna).

III. Coagulation is Accelerated (a.) By Contact with Foreign
Substances of all kinds ; hence, threads or needles introduced into
arteries are rapidly covered with fibrin. Even the introduction of
air-bubbles into the circulation accelerates it, and the pathologically
altered wall of a vessel acts like a foreign body. Blood shed from
an artery rapidly coagulates on the Avails of vessels, on the surfaces
exposed freely to air, and on the rods or twigs by which it is beat.
The passage through it of indifferent gases, such as N. and H., and
the addition of H 2 have the same effect.

(b.) Heating from 39 to 55C., rapidly facilitates coagulation
(Hewson).

(c.) Agitation of the blood, as shown by Hewson and Hunter.

IV. Rapidity of Coagulation. Amongst vertebrates, the blood of
birds (especially of the pigeon), coagulates almost momentarily; in
cold-blooded animals, coagulation occurs much more slowly, while
mammals stand midway between the two. [The blood of a fowl begins
to coagulate in a-half to one and a-half minute ; that of a pig, sheep,
rabbit, in a-half to one and a-half minute ; of a dog, one to three
minutes ; of a horse and ox, five to thirteen minutes ; of man, three
to four minutes ; solidification is completed in nine to eleven minutes,
but rather sooner in the case of women (Nasse) ]. The blood of
invertebrates, which is usually colourless, forms a soft whitish clot of
fibrin. Even in lymph and chyle, a small soft clot is formed.

V. When coagulation occurs, the aggregate condition of the fibrin-
factors is altered, so that heat must be set free (Valentin, 1884, Schiffer,
Lepine). The rise in the temperature may be ascertained with a very
delicate thermometer.

VI. In blood shed from an artery, the degree of alkalinity diminishes
from the time of its being shed until coagulation is completed (Pfliiger
and Zuntz). This is probably due to a decomposition in the blood,
whereby an acid is developed, which diminishes the alkalinity (p. 2).

VII- Whether or not electricity is developed, is not positively proved. Hermann
supposes that the parts already coagulated are negative, while non-coagulated
parts are positive ; but this has not been clearly shown.

VIII. During coagulation there is a diminution of the in the blood,
although a similar decrease also occurs in non-coagulated blood. Traces
of ammonia are also given oft', which Eichardson erroneously supposed
to be the cause of the coagulation of the blood. [This is refuted (1.)
by the fact that blood, when collected under mercury (whereby no
escape of ammonia is possible), also coagulates ; and (2.) by the follow-

CAUSES OF COAGULATION. 43

ing experiment of Lister : He placed two ligatures on a vein con-
taining blood, moistening one-half of the outer surface of the vein
with ammonia, and leaving the other half intact. The blood coagu-
lated in the first half, and not in the other, owing to the properties of
the wall of the vein of the former being altered. Lister also proved
that blood will remain fluid for hours in a vein after it has been
freely exposed to the air, and even after it has been poured in a thin
stream from one vein to another.] Neither the decrease of nor the
evolution of ammonia seems to have any causal connection with the
formation of fibrin.

29. Cause of the Coagulation of the Blood,

Alexander Schmidt stated that fibrin is formed by the coming-
together of two proteid substances which occur dissolved in the plasma
or liquor sanguinis, viz. : (1.) Fibnnogen, i.e., the substance which yields
the chief mass of the fibrin, and (2.) Fibrinoplastic substance or fibrino-
plastin. In order to determine the coagulation a ferment seems to be
necessary, and this is supplied by (3.) the fibrin-ferment.

[The serous sacs of the body contain a fluid which in some respects closely
resembles lymph. The pericardium contains pericardia! fluid, which in some
animals coagulates spontaneously (e.g., in the rabbit, ox, horse, and sheep), if
the fluid be removed immediately after death. If this be not done till several
hours after death, the fluid does not coagulate spontaneously. The fluid of
the tunica vaginalis of the testis, again, sometimes accumulates to a great
extent, and constitutes hydrocele, but this fluid shows no tendency to coagulate
spontaneously. Andrew Buchanan found, however, that if to the fluid of ascites,
to pleuritic fluid, or to hydrocele fluid, there be added clear blood-serum, then
coagulation takes place, i.e., two fluids neither of which shows any tendency by
itself to coagulate form a clot when they are mixed. He also found that if
"washed blood clot" (which consists of a mixture of fibrin and colourless cor-
puscles) be added to hydrocele fluid, coagulation occurred. Denis mixed unco-
agulated blood with a saturated solution of sodic sulphate, allowed the corpuscles
to subside, and decanted the clear fluid which was mixed with sodic chloride,
until a large amount of precipitate had been obtained. The precipitate, when
washed with a saturated solution of sodic chloride, he called plasmine. If plas-
mine be mixed with water, it coagiilates spontaneously, resulting in the formation
of fibrin, while another proteid remains in solution. According to the view of
Denis, fibrin is produced by the splitting up of plasmine into two bodies fibrin
and au insoluble proteid.]

[Researches Of A. Schmidt- This observer rediscovered the chief facts
already known to Buchanan, viz., that some fluids which do not coagulate
spontaneously, clot when mixed with other fluids, which also show no tendency
to coagulate spontaneously, <:. f j., hydrocele fluid and blood-serum. He proceeded
to isolate from these fluids the bodies which are described as fibrinogen and
nbrinoplastin. The bodies so obtained were not pure, but Schmidt supposed that
the formation of fibrin was due to the interaction of these two proteids. The
reason why hydrocele fluid did not coagulate, he said, was that it contained
nbrinogeu aiid no fibrinoplaatin, while blood -serum contained the latter, but not

44 THE FIBRIN-FACTORS.

the former. Schmidt afterwards discovered that these two substances may be
present in a fluid, and yet that coagulation may not occur (e.g., occasionally in
hydrocele fluid). He supposed, therefore, that blood or blood-serum contained
some other constituent necessary for coagulation. This he afterwards isolated
in an impure condition and called fibrin-ferment (Gamgee). ]

Properties of these Substances. Fibrinogen and fibrinoplastin are

not distinguished from each other by well-marked chemical characters.
Still they differ as follows :

(a.) Fibrinoplastin is more easily precipitated from its solutions than
ftbrinogen.

(I.) It is more readily redissolved when once it is precipitated.

(c.) It forms when precipitated a very light granular powder.

(d.) Fibrinogen adheres as a sticky deposit to the side of the vessel.
It coagulates at 56C.

Both substances closely resemble globulin in their chemical composi-
tion (Kiihne called fibrinoplastin paraglobuliri), and in their reactions
they are not unlike myosin. Like all globulins, they require a trace of
common salt for their solution.

On account of their great similarity, both substances are not usually
prepared from blood-plasma. Fibrinogen is prepared from serous trans-
udations (pericardial, abdominal, or pleuritic fluid, or the fluid of
hydrocele), which contain no fibrinoplastin. Fibrinoplastin is most
readily prepared from serum, in which there is still plenty of fibrino-
plastin, but no fibrinogen.

Preparation of Fibrinoplastin. (a.) Dilute blood-serum with twelve
times its volume of ice-cold water, and almost neutralise it with acetic
acid, [add 4 drops of a 25 per cent, solution of acetic acid to every
120 c.c. of diluted serum]; or (b.) pass a stream of carbonic acid through
the diluted serum, which soon becomes turbid ; and after a time a
fine white powder, copious and granular, is precipitated (Schmidt,
18G2).

[(c.) The serum may be dialysed for a day ; at the end of this time the contents
of the dialyser have become turbid, and when a current of COo is passed through
them, a precipitate of fibrinoplastin is obtained. Schmidt's fibrinoplastin has
also been called SERUM-GLOBULIN (Hammarsten) or PARAGLOBULIN (Kiihue).]

Schmidt found that 100 c.c. of the serum of ox blood yielded 0'7 to O'S grins.;
horse serum, 0"3 to 0'56 grms. of dry fibrinoplastin. Fibrinoplastin occurs not
only in serum, but also in red blood-corpuscles, in the fluids of connective tissue,
and in the juices of the cornea.

[((/.) Method of Hammarsten. All the fibrinoplastin in serum is
not precipitated either by adding acetic acid or by C0 2 . Hammarsten
found, however, that if crystals of magnesium sulphate be added to
complete saturation, it precipitates the whole of the serum-globulin,
but does not precipitate serum-albumin (Gamgee) ; it seems that in

THE FIBRIN-FACTORS. 45

the ox and horse serum-globulin is more abundant than serum-albumin,
while in the dog and rabbit the reverse obtains.]

Preparation of Fibrinogen. This is best prepared from hydrocele
fluid, although it may also be obtained from the fluids of serous
cavities e.g., the pleura, pericardium, or peritoneum. It does not
exist in blood-serum, although it does exist in blood-plasma, lymph, and
chyle, from which it may be obtained by a stream of C0 2 , after the
paraglobulin is precipitated, (a.) Dilute hydrocele fluid with ten to
fifteen times its volume of water, and pass a stream of C0 2 through it ;
or (b.) carefully neutralise it by adding acetic acid, (c.) Add powdered
common salt to saturation to a serous transudation, when a sticky
glutinous (not very abundant) precipitate of fibrinogen is obtained.

[Hammarsten and Eichwald find that, although paraglobulin and
fibrinogen are soluble in solutions of common salt (containing 5 to 8
per cent, of the salt), a saline solution of 12 to 16 per cent, is
required to precipitate the fibrinogen, leaving still in solution para-
globulin, which is not precipitated until the amount of salt exceeds
20 per cent. (Gamgee).]

Hammarsten found that it may be prepared from blood (of the
horse) by first precipitating all the serum-globulin or fibrinoplastin
with crystals of magnesium sulphate, and subsequent filtration, which
removes the corpuscles ; a clear salted plasma is thus obtained. If to
the filtrate a saturated solution of common salt be added, a turbid,
flaky, impure precipitate of fibrinogen is obtained. This may be dis-
solved in dilute common salt, and again precipitated by a saturated
solution of NaCl.

Properties Of the Fibrin-Factors. They are insoluble in pure water, but
dissolve in water containing O in solution. Both are soluble in very dilute
alkalies e.g., caustic soda, and are precipitated from this solution by C0 2 . They
are soluble in dilute common salt like all globulins but if a certain amount of
common salt be added in excess they are precipitated. Very dilute hydrochloric
acid dissolves them, but after several hours they become changed into a body
resembling syntonin or acid-albumin.

Fibrinogen dissolved in a weak solution of common salt (1 to 5 per cent.) is
re-precipitated on adding water, so that it resembles fibrin. Its solution in
common salt coagulates at 52 to 55C. (Hammarsten, Frede"ricq).

[Frederic^ finds that fibrinogen exists as such in the plasma, it coagulates at
56C., and the plasma thereafter is uncoagulable (Gamgee).]

Preparation of the Fibrin-Ferment. Mix blood-serum (ox) with
twenty times its volume of strong alcohol, and filter off the deposit
thereby produced after one month. The deposit on the filter consists
of albumin and. the ferment ; dry it carefully over sulphuric acid, and
reduce to a powder. Triturate 1 gramme of the powder with 65 c.c.m.
of water for ten minutes, and filter. The ferment is dissolved by the

46 FORMATION OF FIBRIN.

water, and passes through the filter, while the coagulated albumin
remains behind (Schmidt).

In the preparation of fibrinoplastin, the ferment is carried down with it
mechanically. The ferment seems to be formed first in fluids outside the body,
very probably by the solution of the colourless corpuscles. More ferment is formed
in the blood the longer the interval between its being shed and its coagulation.
It is destroyed at SOC.

[Gamgee'S Method. Buchanan's "washed blood-clot" (p. 43) is digested in
an 8 per cent, solution of common salt. The solution so obtained possesses in an
intense degree the properties of Schmidt's fibrin-ferment. ]

Coagulation Experiments. According to A. Schmidt, if the pure
solutions of (1) fibrinogen, (2) fibrinoplastin, and (3) fibrin-ferment
be mixed, fibrin is formed. The process goes on best at the tem-
perature of the body ; it is delayed at ; and the ferment is
destroyed at the boiling point. The presence of seems necessary
for coagulation. The amount of ferment appears to be immaterial ;
large quantities produce more rapid coagulation, but the amount of
fibrin formed is not greater.

The amount of salts present has a remarkable relation to coagulation.
Solutions of the fibrin-factors deprived of salts, and redissolved in
very dilute caustic soda, when mixed, do not coagulate until sufficient
NaCl be added to make a 1 per cent, solution of this salt (Schmidt).

When blood or blood-plasma coagulates, all the fibrinogen is used
up, so that the serum contains only fibrinoplastin and fibrin-ferment;
hence, the addition of hydrocele fluid (which contains fibrinogen) to
serum causes coagulation.

According to Hammarsten, fibrin is formed when the ferment is
added to a solution of fibrinogen.

[Hattimarsten's Theory Of Coagulation. Hamrnarsten's researches lead
him to believe that fibrinoplastiu is quite unnecessary for coagulation. According
to him, fibrin is formed from one body, viz., fibrinogen, which is present in plasma
when it is acted upon by the fibrin-ferment ; the latter, however, has not been
obtained in a pure state. Neither he nor Schmidt asserts that this body is of
the nature of a ferment, although they use the term for convenience. It is quite
certain that fibrin may be formed when no fibrinoplastin is present, coagulation
being caused by the addition of calcic chloride or casein prepared in a special way.
But, whether one or two proteids be required, in all cases it is clear that a
certain quantity of salts, especially of NaCl, is necessary.]

30. Source of the Fibrin-Factors.

Al. Schmidt maintains that all the three substances out of which
fibrin is said to be formed, arise from the breaking up of colourless
blood-corpuscles. In the blood of man and mammals fibrinogen exists,
dissolved in the circulating blood as a dissolution product of the

SOURCES OF THE FIBRIN-FACTORS. 47

retrogressive changes of the white corpuscles. Plasma contains
dissolved fibrinogen and serum-albumin. The circulating blood is
very rich in lymph or white cells, much richer, indeed, than was
formerly supposed (Schmidt, Landois). As soon as blood is shed from
an artery, enormous numbers of the colourless corpuscles are dissolved
(Mantegazza) according to Alex. Schmidt 71'7 per cent, (horse).
First, the body of the cell disappears, and then the nucleus (Hlava).
The products of their dissolution are dissolved in the plasma, and one
of these products' is fibrinopltistin. At the same time the fibrin-ferment
is also produced, so that it would seem not to exist in the intact blood-
corpuscles. Fibrinoplastin and fibrin -ferment are also produced by
the " transition forms " of blood-corpuscles, i.e., those forms which are
intermediate between the red and the white corpuscles. They seem to
break up immediately after blood is shed. The blood-plates (p. 21),
are also probably sources of these substances.

In amphibians and birds, the red nucleated corpuscles rapidly
break up after blood is shed, and yield the substance or substances
which form fibrin. Al. Schmidt convinced himself that in these
animals fibrinogen is also a constituent of the blood-corpuscles.

It is clear, therefore, according to Schmidt's view, that as soon as
the blood-corpuscles, white or red, are dissolved, the fibrin-factors pass
into solution, and the formation of fibrin by the union of the three
substances will ensue.

[It is worthy of remark to recall the conclusion arrived at by And.
Buchanan, viz., that the potential element of his "washed blood-clot" resided
in the colourless corpuscles, "primary cells or vesicles." He, like Schmidt, found
that the buffy-coat of horse's blood, which is very rich in white corpuscles,
produced coagulation rapidly. Buchanan compared the action of his washed clot
to that of rennet in coagulating milk.]

Pathological. Al. Schmidt and his pupils, Jakowicki and Birk, have shown
that some ferment, probably derived from the dissolution of colourless corpuscles,
is found in circulating blood, and that it is more abundant in venous than in
arterial blood, while it is most abundant in shed blood. It is specially remarkable
that in septic fever the amount of ferment in blood may increase to such an extent
as to permit the occurrence of spontaneous coagulation (thrombosis), which may
even produce death (Arn. Kb'hler). In febrile cases generally, the amount of
ferment is somewhat more abundant (Edelberg and Birk). After the injection
of ichor into the blood an enormous number of colourless corpuscles are dissolved
(F. Hoffmann).

31. Relation of the Red Blood- Corpuscles to the

Formation of Fibrin.

That the red blood-corpuscles may participate in the production of
fibrin is proved by many experiments.

48 RED CORPUSCLES AND FIBRIN-FORMATION.

Hoppe-Seyler showed that the nucleated blood-corpuscles of birds,
when treated with water, give a copious precipitate which resembles
fibrin. Heynsius observed a similar result after the blood of fowls
had been acted upon by water and dilute solution of common salt, and
he also states that nearly 90 per cent, of the total fibrin may be
obtained from the washed blood-corpuscles of the horse, when the
corpuscles are gradually dissolved. Semmer discovered that he could
cause defibrinated frog's blood to coagulate by mixing it with 4 to 6 times
its volume of water. On adding 10 to 12 drops of a 0'2 per cent,
solution of soda to 1 c.c.m. of defibrinated frog's blood, Semmer and A.
Schmidt found that it became converted into a structureless glutinous
mass, in which neutralisation with acetic acid produced fibres of fibrin.
No fibrin was formed from serum. The same observers diluted 4 c.c.m.
of defibrinated frog's blood with 20 c.c.m. of water containing CO.,.
The haemoglobin was thereby dissolved in the water, while the colour-
less stromata fell to the bottom. When this deposit was mixed with a
solution of sodium hydrate, a similar glutinous mass was obtained,
which yielded fibrin on being neutralised with acetic acid. No such
result was obtained from haemoglobin.

In 1874, Landois observed under the microscope that the stromata
of the red blood- corpuscles of mammals passed into fibrin. If a drop
of defibrinated rabbit's blood be placed in serum of frog's blood, with-
out mixing them, the red corpuscles can be seen collecting together ;
their surfaces are sticky, and they can only be separated by a certain
pressure on the cover-glass, whereby some of the new spherical
corpuscles are drawn out into threads. The corpuscles soon become
spherical, and those at the margin allow the haemoglobin to escape,
when the decolourisation progresses, from the margin inwards, until at
last there remains a mass of stroma adhering together. The stroma-
substance is very sticky, but soon the cell-contours disappear, and the
stromata adhere and form fine fibres. Thus (according to Landois)
the formation of fibrin from red blood-corpuscles can be traced step by
step. The red corpuscles of man and animals, when dissolved in the
serum of other animals, show much the same phenomena.

Stroma-Fibrin and Plasma-Fibrin. Landois calls fibrin formed
direct from stroma, stroma-fibrin. Fibrin which is formed in the usual
way by the fibrin-factors he calls plasma-fibrin. The stroma-fibrin is
closely related chemically to stroma itself; and as yet the two kinds of
fibrin have not been sharply distinguished chemically. Substances which
rapidly dissolve red corpuscles cause extensive coagulation, e.g., injection
of bile or bile salts, or lake-coloured blood, into arteries (Naunyn and
Francken). After the injection of foreign blood the newly-injected
blood often breaks up in the blood-vessels of the recipient, while

COMPOSITION OF PLASMA AND SERUM, 49

the finer vessels are frequently found plugged with small thrombi
(see Transfusion, p. 61).

Coagulable Fluids. With regard to coagulability, fluids containing proteids
may be classified thus :

(1.) Those that coagulate spontaneously, i.e., blood, lymph, chyle.

(2.) Those capable of coagulating, e.g., fluids secreted pathologically in serous
cavities ; for example, hydrocele fluid, which, as usually containing fibrinogen only,
does not coagulate spontaneously, coagulates on the addition of fibrinoplastin and
ferment (or of blood-serum in which both occur).

(3.) Those which do not coagulate, e.g., milk or seminal fluid, which do not seem
to contain fibrinogen.

32. Chemical Composition of the Plasma and

Serum.

I. Proteids occur to the amount of 8 to 1 per cent, in the plasma.
Only 0'2 per cent, of these go to form fibrin. When coagulation has
taken place, and after the separation of the fibrin, the plasma becomes
converted into serum. The S. G. of human serum is 1,027 to 1,029. It
contains several proteids. [According to Hammarsten, human serum
contains 9'2075 per cent, of solids, of these, 3'103 = serum-globulin,
and 4'516 = serum-albumin, i.e., in the ratio of 1 : T511.]

(a.) Serum-Globulin (Th. Weyl) or Para-Globulin 2-4 p. c., was
formerly believed to occur in much smaller amount than it actually
does. Hammarsten found that if serum be diluted with two volumes
of water, and crystals of magnesium sulphate be added to saturation,
serum-globulin is precipitated, but not serum-albumin. In the serum
of the horse and ox serum-globulin is more abundant than serum-
albumin, while in the serum of the rabbit and dog the reverse is
the case. It is soluble in 10 per cent, solution of common salt, and
coagulates at 75C.

[Serum-globulin was carefully described by Panum under the name of "Serum-
casein;" by Al. Schmidt, as " Fibrino-plastic substance;" and by Kiihne, as
"Para-globulin."]

As already mentioned, it may also be precipitated, in part, by diluting serum
with 10 to 15 vols. of water, and passing a stream of C0 2 through it (p. 44). If a
trace of acetic acid be added to serum after the separation of the serum-globulin,
Kiihne finds that a fine precipitate of what he calls soda-albuminate occurs. [It
is, however, highly doubtful if an alkali-albuminate does occur in the blood.
Hammarsten found that C0 2 does not precipitate all the serum-globulin, so that
it is improbable that Kiihne's soda-albuminate exists as a distinct substance
in serum.]

According to A. E. Burckhard, magnesium sulphate not only precipitates
serum-globulin, but also another proteid substance more closely resembling
albumin. During hunger the globulin increases and the albumin diminishes.

Serum-Albumin. Its solutions begin to be turbid at 60C.,
and coagulation occurs at 73C., the fluid becoming slightly more

4

50 COMPOSITION OF PLASMA AND SERUM.

alkaline at the same time. The amount is about 3-4 p. c. (Fredmcq).
If sodium chloride be cautiously added to serum, the coagulating
temperature may be lowered to 50C. It has a rotatory power of 56.
It is changed into syntonin or acid-albumin by the action of dilute
HC1, and by dilute alkalies into alkali-albuminate.

[Although serum-albumin is closely related to egg -albumin they differ :
(a.) as regards their action upon polarised light; (b. ) the precipitate produced by
adding HC1 or HN0 3 is readily soluble in 4 c.c.m. of the reagent in the case of
serum-albumin, while the precipitate in egg-albumin is dissolved with very great
difficulty ; (c. ) egg-albumin, injected into the veins, is excreted in the urine as a
foreign body, while serum-albumin is not (Stockvis).

Serum-albumiu has never been obtained free from salts, even when it is diatysed
for a very long time, as was maintained by Aronstein, whose results have not been
confirmed by Heynsius, Haas, Huizinga, Salkowski, and others.]

After all the para-globulin (serum-globulin) in serum is precipitated by
magnesium sulphate, serum-albumin still remains in solution. If this solution
be heated to 40 or 50C. a copious precipitate of non-coagulated serum-albumin is
obtained, which is soluble in water. If the serum-albumin be filtered from the
fluid, and if the clear fluid be heated to over 60C., FredeYicq found that it becomes
turbid from the precipitation of other proteids; the amount of these other bodies,
however, is small.

II. Fats (O'l to 0'2 per cent.). Neutral fats (tristearin, tripalmitin,
triolein) occur in the blood in the form of small microscopic granules,
which, after a meal rich in fat (or milk), render the serum quite
milky.

The amount of fat in the serum of fasting animals is about 0'2 per
cent.; during digestion 0'4 to 0'6 per cent.; and in dogs fed on a diet
rich in fat it may be 1'25 per cent. There are also minute traces of
fatty acids (succinic). Rohrig showed that soluble soaps i.e., alkaline
salts of the fatty acids cannot exist in the blood. \Cholcsterin may
be considered along with the fats. It occurs in considerable amount
in nerve-tissues, and, like fats, is extracted by ether from the dry
residue of blood-serum. Hoppe-Seyler found 0'019 to 0*314 per cent,
in the serum of the blood of fattened geese. There is no fat in the red
blood-corpuscles (Hoppe-Seyler). Lecithin (and protagou) occur in
serum and also in the blood-corpuscles.]

III. Traces of Grape Sugar (O05 per cent.) occur normally in
blood and serum, and also a trace of glycogen.

The amount of grape sugar in the blood increases with the absorption of sugar
from the intestine, and this increase is most obvious in the blood of the portal
and hepatic veins; there is also a slight increase in the arterial blood, but there it
is rapidly changed. The presence of sugar is ascertained by coagulating blood by
boiling it with sodium sulphate, pressing out the fluid and testing it for sugar
with Fehling's solution (Cl. Bernard). Pavy coagulates the blood with alcohol.

IV. Extractives. Kreatin, urea (O'Ol to 0'085 per cent, in the

COMPOSITION OF PLASMA AND SERUM. 51

dog), hippurie acid, succinic acid, and uric acid (more abundant in gouty
conditions), hypoxanthin, all occur in very small amounts.

The plasma and serum contain a yellow pigment, or perhaps several
pigments. One of these is called cholepyrrhin (horse, calf), and is
identical with the bile pigment of the same name (Hammarsten).
[Rabbit's serum is colourless.] Thudichum regards the yellow pigment
as lutein ; Maly, as hydrobilirubin; and MacMunn as choletelin.

V. Sarcolactic Acid and Indican, also in small amount.

VI. Salts. The amount of inorganic salts ('085 to '09 per cent.)
contained in the serum is slightly less than in the plasma, as a small
amount of lime and magnesic phosphate is removed by the fibrin
(Briicke). The most abundant salt is sodium chloride (0'5 per cent.),
and next to it sodium carbonate [which exists in the plasma, most
probably in the condition of sodium hydric carbonate (NaHC0 3 ).
There is a small amount of potassic chloride, and also sulphuric and
phosphoric acids, lime and magnesia. It is most important to note
that the soda salts are far more abundant in the serum than the
potassium salts. The ratio may be as high as 10:1.]

Salts in human blood-serum (Hoppe-Seyler).

Sodic Chloride. . 4'92 per 1000.

,, Sulphate, ..... 0'44 ' ,,

,, Carbonate, . . 0'21 ,,

,, Phosphate, . O'lo ,,

Calcic Phosphate, . ") A -

TV r L/ l O . .

.Magnesic ,, . . . . )

VII. Water about 90 per cent.

33. The Gases of the Blood,

Absorption of Gases by Solid Bodies and by Fluids.

Absorption by Solid Bodies. A considerable attraction exists between the
particles of solid porous bodies and gaseous substances, so that gases are attracted
and condensed within the pores of solid bodies i.e., the gases are absorbed.
Thus, one volume of boxwood charcoal (at 12C. and ordinary barometric pressure)
absorbs 35 volumes C0 2 9'4 vol. 7 '5 vol. N 1'75 vol. H. Heat is always
formed when gases are absorbed, and the amoiint of heat evolved bears a relation
to the energy with which the absorption takes place. Non-porous bodies are
similarly invested by a layer of condensed gases on their surface.

By Fluids. Fluids can also absorb gases. A known, quantity of fluid at
different pressures always absorbs the same volume of gas. Whether the pressure
be great or small, the volume of the gas absorbed is equally great (W. Henry).
But according to Boyle and Mariotte's law (1679), when the pressure within the
same volume of gas is increased, the volume varies Inversely as the pressure.

Hence it follows that, with varying pressure, the volume of gas absorbed remains

52 GASES OF THE BLOOD.

the same, but the quantify of gas (weight, density) is directly proportional to th?
pressure.. If the pressure 0, the weight of the gas absorbed must also = 0.
As a necessary result of this, we see that (1.) fluid* can be freed of their absorbed
gases in a vacuum under an air-pump.

Coefficient Of absorption means the volume of a gas (at 0C) which is absorbed
by a unit of volume of a liquid (at 760 mm. Hg) at a given temperature. The volume
of a gas absorbed, and therefore the coefficient of absorption, is quite independent
of the pressure, while the weight of the gas is proportional to it. Temperature, has
an important influence on the coefficient of absorption. With a low temperature,
it is greatest; it diminishes as the temperature increases; and at the boiling point
it = 0. Hence, it follows that (2.) Absorbed gases may be expelled from fluids
simply by causing the fluids to boil. The coefficient of absorption diminishes for
different fluids and gases, with increasing temperature, in a special, and by no
means uniform, manner, which must be determined empirically for each liquid
and gas. Thus the coefficient of absorption for COj in water diminishes with an
increasing temperature, while that for H in water remains unchanged between
and 20T.

Diffusion and Absorption of Gases.

Diffusion Of Gases. Gases which do not enter into chemical combinations with
each other, mix with each other in quite a regular proportion. If, e.g., the necks
of two flasks be placed in communication by means of a glass or other tube, and if
the lower flask contain C0 2 , and the upper one H, the gases mix quite indepen-
dently of their different specific gravities, both gases forming in each flask a perfectly
uniform mixture. This phenomenon is called the diffusion ofyases. If a porous
membrane be previously inserted between the gases, the exchange of gases still
goes on through the membrane. But (as with endosmosis in fluids) the gases pass
with unequal rapidity through the pores, so that at the beginning of the experi-
ment a larger amount of gas is found on one side of the membrane than on the
other. According to Graham, the rapidity of the diffusion of the gases through
the pores is inversely proportional to the square root of their specific gravities.
(According to Bun sen, however, this is not quite correct.)

Different Gases forming a Gaseous Mixture do not Exert Pressure

Upon One another. Gases, therefore, pass into a space filled with another gas,
as they would pass into a vacuum. If the surface of a fluid containing absorbed
gases be placed in contact with a very large quantity of another gas, the absorbed
gases diffuse into the latter. Hence, absorbed gases can be removed by (3.)
passing a stream of another gas through the fluid, or by merely shaking up the fluid
with another gas.

If two or more gases are mixed in a closed space over a fluid, as the different
gases existing in a gaseous mixture exert no pressure upon each other, the several
gases are absorbed. The weight of each absorbed is proportional to the pressure
under which each gas would be, were it the only gas in the space. This pressure
is called the partial pressure of a gas (Bunsen). The absorption of gases from their
mixtures, therefore, is proportional to the partial pressure. The partial pressure
of a gas in a space is at the same time the expression for the tension of the gas
absorbed by a fluid.

The air contains 0'2096 volume of O, and 0'7904 volume N. If 1 volume of
the air be placed under a pressure, P, over water, the partial pressure under which
O is absorbed = 0'2096 . P ; that for N, = 0'7904 . P. At 0C., and 760 m.m.
pressure, 1 volume of water absorbs '02477 volume of air, consisting of 0'00862
volume 0, and '01615 volume N. It contains, therefore, 34 per cent. 0, and
66 per cent. N. Therefore, water absorbs from the air a mixture of gases containing
a larger percentage of than the air itself.

GASES OF THE BLOOD.

34. Extraction of the Blood Gases.

The extraction of the gases from the blood, and their collection for chemical
analysis, are carried out by means of the mercurial pump (C. Ludwig). Fig. 15
shows in a diagrammatic form the arrangement of Pnuger's gas-pump.

It consists of a RECEPTACLE FOR THE BLOOD, or "BLOOD-BULB" (A), a glass-
globe capable of containing 250 to 300 c.c.m., connected above and below with
tubes, each of which is provided with a stop-cock, and b ; b is an ordinary stop-
cock, while a has through its long axis a perforation which opens at z, and is
so arranged that, according to the position of the handle, it leads up into the

Fig. 15.

Scheme of Pfkiger's gas-pump A, blood-bulb ; a, stop-cock, with a longitudinal
perforation opening upwards ; a', the same opening downwards ; b and c,
stop-cocks ; B, froth-chamber ; d, e, f, stop-cocks ; G, drying-chambers,
containing sulphuric acid and pumice-stone ; D, tube, with manometer, y.

54: EXTRACTION OF THE BLOOD-GASES.

blood bulb (position x, a), or downwards through the lower tube (position
x', a'). This blood-bulb is first completely emptied of air (by means of a mercurial
air-pump), and then carefully weighed. One end (x') of it is tied into an artery
or a vein of an animal, and when the lower stop-cock is placed in the position
(x a) blood flows into the receptacle. When the necessary amount of blood is
collected, the lower stop-cock is put into the position, x'. a', and the blood-
bulb, after being cleaned most carefully, is weighed to ascertain the weight of the
amount of blood collected. The second part of the apparatus consists of the froth-
chamber, B, leading upwards and downwards into tubes, each of which is pro-
vided with an ordinary stop-cock, c and d. The froth-chamber, as its name
denotes, is to catch the froth which is formed during the energetic evolution of the
gases from the blood. The lower aperture of the froth-chamber is connected by
means of a well-ground tube with the blood-bulb, while above it communicates
with the third part of the apparatus, the drying-chamber, G. This consists of a
U-shaped tube, provided below with a small glass-bulb, which is half filled with
sulphuric acid, while in its limbs are placed pieces of pumice-stone also moistened
with sulphuric acid. As the blood-gases pass through this apparatus (which may
be shut off by the stop-cocks, e and/) they are freed from their watery vapour by
the sulphuric acid, so that they pass quite dry through the stop-cock, /. The
short well -ground tube, D, is fixed to/ and to the former is attached the small
barometric tube or manometer, y, which indicates the extent of the vacuum. From
D we pass to the pump proper. This consists of two large glass-bulbs which are
continued above and below into open tubes ; the lower tubes, Z and iv, being
united by a caoutchouc tube, G. Both the bulbs and the caoutchouc tube contain
mercury the bulbs being about half-full, and F being larger than E. The bulb,
E, is fixed ; but F can be raised or lowered by means of a pulley with a rack and
pinion motion. If F be raised, E is filled ; if F be lowered, E is emptied. The
upper end of E divides into two tubes, g and A. of which (j is united to D. The
ascending tube, h- gas-delivery tube is very narrow, and is bent so that its
free end dips into a vessel containing mercury (u) a pneumatic trough and the
opening is placed exactly under the tube for collecting the gases, the eudiometer,
J, which is also filled with mercury. Where g and H unite, there is a two-way
stop -cock, which in one position, H, places E in communication with A, B, G, I)
the chambers to be exhausted, and in the position, K, shuts off A, B, G, D, and
places the bulb, E, in communication with the gas-delivery tube, It, and the
eudiometer, J.

B, G, D are completely emptied of air, thus : The stop-cock is placed
in the position, K ; raise F until drops of mercury issue from the fine tube, i (not
yet placed under J) ; place the stop-cock in the position H, lower F ; stop-cock in
position, K, and so on until the barometer, y, indicates a complete vacuum. J is
now placed over i. Open the cocks, c and b, so that the blood-bulb, A, communi-
cates with the rest of the apparatus, and the blood-gases froth up in B, and after
being dried in G pass towards E. Lower F, and they pass into E ; stop-cock
in position, K, raise F, and the gases are collected in J under mercury. The
repeated lowering and raising of F with the corresponding position of the stop-
cocks ultimately drives all the gases into J. The removal of the gases is greatly
facilitated by placing the blood-bulb, A, in a vessel containing water at 60C.

It is well to remove the gases from the blood immediately after it is collected
from a blood-vessel, because the undergoes a diminution if the blood be kept.
Of course, in making several analyses it is difficult to do this, and the best plan to
pursue in that case is to keep the receptacles containing the blood on ice.

Mayow (1670) observed that gases were given off from blood in vacua. Magnus
(1837) investigated the percentage composition of the blood-gases. The more
important recent investigations have been made by Lothar Meyer (1857), and by
the pupils of C. Ludwig and E. Pfliiger.

ESTIMATION OF THE BLOOD-GASES. 55

35. Quantitative Estimation of the Blood-Gases.

The gases obtained from blood consist of 0, C0 2 and N. Pfliiger
obtained (at 0C. and 1 metre Hg pressure), 47'3 volumes per cent,
consisting of

O 16'9 per cent. - CO., 29 per cent. - N. 1'4 per cent.
As is shown in Fig. 15, the gases are obtained in an eudiometer,
i.e., in a narrow tube, J, closed at one end, and with a very exact scale
marked on it, and having two fine platinum wires melted into its upper
end, with their free-ends projecting into the tube (p and ??-).

(1.) Estimation Of the COs. A small ball of fused caustic potash, fixed on a
platinum wire, is introduced into the mixture of gases through the lower end of
the eudiometer under cover of the mercury. The surface of the potash ball it
moistened before it is introduced. The C0 2 unites with the potash to form
potassium carbonate. After it has been in for a considerable time (24 hours), it
is withdrawn iu a similar manner. The diminution in volume indicates the
amount of C0 2 absorbed.

(2.) Estimation Of the 0. () Just as in estimating the COo. a ball of phos-
phorus on a platinum wire is introduced into the eudiometer (Bertholet); it
absorbs the and forms phosphoric acid. Another plan is to employ a small
papier-mache ball saturated with pyrogalliQ acid in caustic potash, which rapidly
absorbs (Liebig). After the ball is removed, the diminution in volume
indicates the quantity of 0.

(b.) The is most easily and accurately estimated by exploding it in the
eudiometer (Volta and Bunsen). Introduce a sufficient quantity of H into
the eudiometer, and accurately ascertain its volume ; an electrical spark is
now passed between the wires, p and n, through the mixture of gases ; the and H
unite to form water, which causes a diminution in the volume of the gases in the
eudiometer, of which ^ is due to the used to form water (H 2 0).

(c.) Estimation Of the N. When the C0 2 and are estimated by the above
method, the remainder is pure N.

36. The Blood Gases.

I. Oxygen exists in arterial blood (dog) on an average to the
extent of 17 volumes per cent, (at 0C. and 1 metre Hg pressure)
(Pfliiger). According to Pfliiger, arterial blood (dog) is saturated to
^ with 0, while, according to Hu'fner, it is saturated to the extent
of yi. In venous blood the quantity varies very greatly; in the blood
of a passive muscle 6 volumes per cent, have been found ; while in the
blood after asphyxia it is absent, or occurs only in traces. It is
certainly more abundant in the comparatively red blood of active
glands (salivary glands, kidney), than in ordinary dark venous blood.

The in Blood occurs (a.) simply absorbed in the plasma. This is
only a minimal amount, and does not exceed what distilled water
at the temperature of the body would take up at the partial pressure
of the in the air of the lungs (Lothar Meyer). According to

56 THE BLOOD-GASES.

Fernet, serum takes up slightly more O than corresponds to the
pressure, and this is. perhaps, due to the trace of hemoglobin con-
tained in the plasma or the serum, and which is derived from the
solution of red corpuscles.

(b.) Almost the total of the Hood is chemically united, and, therefore,
not subject to the law of absorption. It is loosely united to the
haemoglobin of the red corpuscles, with which it forms oxyhcemoglobin
(p. 29).

The absorption of this quantity of is completely independent of pressure;
hence, animals confined in a closed space until they are nearly asphyxiated, can
use up almost all the O from the surrounding atmosphere. The fact of the union
being independent of pressure is proved by the following: The blood only gives
off copiously its chemically united 0, when the atmospheric pressure is lowered
to 20 millimetres, Hg. (Worm Miiller) ; and, conversely, blood only takes up a
little more when the pressure is increased to 6 atmospheres (Bert).

Physical Methods of obtaining from Blood. Notwithstanding
this chemical union between the Hb and 0, however, the total of the
blood can be expelled from its state of combination by those means
which set free absorbed gases (a.) by introducing blood into a torri-
cellian vacuum ; (b.) by boiling ; (c.) by the conduction of other gases
[H,N,CO or NO] through the blood, because the chemical union
of the oxyhsemoglobin is so loose that it is decomposed even by these
physical means.

Chemical Keagents. Amongst chemical reagents the following re-
ducing substances ammonium sulphide, sulphuretted hydrogen, alkaline
solutions of sub-salts, iron filings, &c., rob blood of its (p. 30).

With regard to the taking up of 0, the total quantity of blood behaves
exactly like a solution of haemoglobin free from (Preyer.) The
amount of iron in the blood (0'55 in 1,000 parts) stands in direct
relation to the amount of Hb; this to the quantity of blood-corpuscles;
and this, in turn, to the specific gravity of the blood. The amount of
in the blood, therefore, is nearly proportional to the specific gravity
of the blood, and it is also in proportion to the amount of iron in the
blood. Picard affirms that 2 '3 6 grammes of iron in the blood can
fix chemically 1 grrn. 0; while, according to Hoppe-Seyler, the pro-
portion is 1 atom iron to 2 atoms 0.

When blood is kept long outside of the blood-vessels, the quantity of gradually
diminishes, and if it be kept for a length of time at a high temperature it may
disappear altogether. This depends upon decomposition occurring within the
blood. By this decomposition in the blood (cadaveric phenomenon), reducing
substances are formed which consume the 0. All kinds of blood, however, do not
act with equal energy in consuming 0, e.g., venous blood from active muscles acts
most energetically, while that from the hepatic vein has very little effect. C0 2
appears in the blood in place of the 0, and the colour darkens. The amount of
C0 2 produced is sometimes greater than that of the O consumed.

THE BLOOD-GASES. 57

If blood (or a solution of oxyha?moglobin) be acted upon by adds (e.g., tartaric
acid) until it is strongly acid, O may be pumped out in considerably less amount,
while the formation of C0 2 is not increased. We must, therefore, assume that,
during the decomposition of the Hb caused by the acids (p. 33), a decomposition
product becomes more highly oxidised by the intense chemical union of the at
the moment of its origin (Lothar Meyer, Zuntz, Strassburg). The same phe-
nomenon occurs when oxyhaMiioglobin is decomposed by boiling.

37. Is Ozone (0 8 ) Present in Blood?

On account of the numerous and energetic oxidations which occur
in connection with the blood, the question has often been raised as to
whether the of the blood exists in the form of active O (0 8 ), or
ozone. Ozone, however, is contained neither in the blood itself
(Schonbein) nor in the blood-gases obtained from it. Nevertheless,
the red corpuscles (and Hb) have a distinct relation to ozone.

(1.) Tests for Ozone. Hremoglobiu acts as a conveyer of ozone, i.e., it is able to
remove the active of other bodies and to convey or transfer it at once to other
easily oxidisable substances, (a.) Turpentine which has been exposed to the air
for a long time always contains ozone. The tests for the latter are starch and
potassium iodide, the ozone decomposing the iodide when the iodine strikes a blue
with the starch. (6.) Freshly-prepared tincture of guaiacum is also rendered blue
by ozone. If some tincture of guaiacum be added to turpentine there is no reaction,
but on adding a drop of blood a deep blue colour is immediately produced, i.e.,
blood takes the ozone from the turpentine and conveys it at once to the dissolved
guaiacum, which becomes blue (Schonbein, His). It is immaterial whether the
Hb contains or not.

(2.) It has been asserted also that haemoglobin acts as an ozone-
producer, i.e., that it can convert the ordinary of the air into ozone.
Hence the reason why red blood-corpuscles alone render guaiacum
blue. This reaction succeeds best when the guaiacum solution is
allowed to dry on blotting-paper, and a few drops of blood (diluted
5 to 10 times) are poured on it. That the Hb forms ozone from the
surrounding O, is shown by the experiment in which even red blood-
corpuscles containing carbonic oxide were found to cause the blue
colour (Kiiline and Scholz).

According to Pfliiger, however, these reactions only occur from
decomposition of the Hb, and as a result of this view the blood-
corpuscles cannot be regarded as producers of ozone.

Sulphuretted hydrogen is decomposed by blood (as by ozone itself) into sulphur
and water. Hydric peroxide is decomposed by blood into and water [but this
reaction is prevented by the addition of a small amount of hydrocyanic acid
(Schonbein)]. Crystallised Hb does not do this, and H 2 2 may be cautiously
injected into the blood-vessels of animals. This would show that unchanye.d Hb
does not produce ozone.

Various Forms Of Oxygen. There are three forms of oxygen: (1.) The

58 CARBONIC ACID AND NITROGEN IN BLOOD.

ordinary oxygen (0 2 ) in the air. (2.) Active or nascent oxygen (0), which never
can occur iu the free state, but the moment it is formed acts as a powerful
oxidising agent and produces chemical compounds. It converts water into hydric
peroxide the N of the air into nitrous and nitric acids, and even CO into C0 2 ,
which ozone does not. It certainly plays an important part in the organism. (3.)
Ozone (Oz), which is formed by the decomposition of several molecules of ordinary
oxygen (0 2 ) into two atoms of 0, and the appropriation of each of these atoms by a
molecule of undecomposed oxygen. It is oxygen condensed to of its volume.

38. Carbonic Acid and Nitrogen in Blood.

II. Carbonic Acid. In arterial blood there are about 30 volumes per
cent, of CO., (at 0C. and 1 metre pressure Setschenow); but in venous
blood the amount is very variable ; e.g., in the venous blood of passive
muscles there are 35 volumes per cent. (Sczelkow), while in the blood
of asphyxia there may be 52'6 volumes per cent. The amount of CO.,
in the lymph of asphyxia is less than that in the blood (Buehner,
Gaule).

The CO., in the entire mass of the blood may be extracted from it or
completely pumped out, but during the process of evacuation, or removal
of the gas, a new property of the red blood-corpuscles is produced,
whereby they assume the function of an acid and thus aid in the chemical
expulsion of the CO.,. This acid-like property of the red corpuscles
occurs especially in the presence of and heat.

(A.) The C0 2 in the Plasma. The largest portion of the C0 2 belongs to
the- plasma (or serum) and it appears all to be in a state of chemical
combination. Serum takes up C0 quite independently of pressure,
hence it cannot be merely absorbed. A certain part of the C0. 2 can be
removed from the serum (plasma) by the torricellian vacuum, while
another part is obtained only after the addition of an acid. [This is
called the "fixed" CO.,, while the former is known as the "loose"
CO,.]

The union of C0 2 in the serum may take place in the following
ways :

(1.) C0 2 is united to the soda of the plasma in the form of " sodic
carbonate." This portion of the CO., can only be displaced from its
combination by the addition of an acid. (In depriving blood of its
gases the red corpuscles play the role of an acid.)

(2.) A portion of the CO., is loosely united to sodic carbonate in
the form of sodic bicarbonate; the carbonate takes up 1 equivalent of
C0 2 ; Na 2 C0 3 + C0 2 + H 2 = 2 NaHC0 3 . This C0 2 may be pumped out,
as in the process the bicarbonate splits up again into the neutral
carbonate and CO.,.

CARBONIC ACID AND NITROGEN IN BLOOD. 59

Preyer has objected to this view on the ground that blood is alkaline in reaction,
whilst all solutions that contain C0 2 in a state of absorption, or loose chemical
combination, are always acid. Pflliger and Zuntz showed that blood, after being
completely saturated with C0 2 , still remains alkaline.

As the bicarbonate only gives up its C0 2 very slowly in vacua, while blood gives
off its COo very energetically, perhaps the soda, united with an albuminous body,
combines with the CC>2 and forms a complex compound, from which the C0 2 is
rapidly given off in vacua.

(3.) A minimal portion of the C0 2 may be chemically united in the
plasma with neutral sodic phosphate (Fernet). One equivalent of this
salt can fix 1 equivalent of C0 2 , so acid sodium phosphate and acid
sodium carbonate are formed, Na 2 HP0 4 + C0 2 + H 2 = NaH 2 P0 4
+ NaH,C0 3 (Hermann). When the gases are removed the C0 2
escapes, and neutral sodic phosphate remains.

It is probable, however, that almost all the sodic phosphate found in the blood-
ash arises from the burning of lecithin; we have, therefore, to consider only the
very small amount of this salt which occurs in the plasma (Hoppe-Seyler and
Sertoli).

(B.) The CO., in the Blood-Corpuscles. The red corpuscles contain
CCX, in a loose chemical combination; for (1.) a volume of blood can
fix nearly as much CO., as an equal volume of serum (Ludwig, Al.
Schmidt) ; and (2.) with increasing pressure the absorption of CO., by
blood takes place in a different ratio from what occurs with serum
(Pfliiger, Zuntz). The red corpuscles may fix more CO., than their
own volume, and the union of the CO., seems to depend upon the Hb,
for Setschenow found that, when Hb was acted on by C0 2 , its power
of fixing the latter was increased, which is perhaps due to the forma-
tion of some substance (paraglobulin) more suited for fixing CO.,.
The colourless corpuscles also fix CO., after the manner of the serum-
constituents, and to the extent of to T V of the absorbing power of
serum (Setschenow).

III. Nitrogen exists in the blood to the extent of 14 to TG vol.
per cent., and it appears to be simply absorbed.

It is still doubtful whether a small part of the N exists chemically united in the
red corpuscles. Outside the body when blood is heated, and when there is a free
supply of and warmth, it gives off very minute quantities of ammonia, which
are perhaps derived from the decomposition of some salt of ammonia as yet unknown
(Ktihne and Strauch).

39. Arterial and Venous Blood.

Arterial blood contains in solution all those substances which are
necessary for the nutrition of the tissues, those which are employed in
secretion ; it also contains a rich supply of 0. Venous blood must

60 ARTERIAL AND VENOUS BLOOD.

contain less of all these, but in addition it holds the used-up or effete
substances derived from the tissues, and the products of their retro-
gressive metabolism being more numerous, there is in venous blood a
larger amount of C0 . It is evident also that the blood of certain
veins must have special characters, e.g., that of the portal and
hepatic veins.

The following are the most important points of difference between
arterial and venous blood :

Arterial Blood contains

more 0,
less C0 2 ,
more water,
more fibrin,
more extractives,

more sugar,

fewer blood-corpuscles,

less urea.

It is bright red and not

dichroic.

more salts. As a rule it is 1C. warmer.

The bright red colour of arterial blood depends on the presence of
oxyhsemoglobin, whilst the dark colour of venous blood is due to its
smaller proportion of oxyhsemoglobin, and the quantity of reduced
luemoglobin which it contains. The dark change of colour is not to
be attributed to the larger quantity of C0. 7 in venous blood (Marchand);
for if equal qualities of be added to two portions of blood, and if
CO., be added to one of them, the colour is not changed (Pfliiger).

40. Quantity of Blood.

In the adult the quantity of blood is equal to jV P ai 't f the body-
weight (Bischoff), in newly-born children -^ (Welcker).

According to Schiicking, the amount of blood in a newly-born child depends to
some extent upon the time at which the umbilical cord is ligatured. The amount
= T of the body-weight when the cord is tied at once, while if it is tied some-
what later it may be J. Immediate ligature of the cord may, therefore, deprive
a newly-born child of 100 grammes of blood. Further, the number of corpuscles
is less in a child after immediate ligature of the umbilical cord, than when it is
tied somewhat later (Helot).

Various methods are adopted to ascertain the amount of blood, but
perhaps that of Welcker is the best.

The methods of Valentin (1838), and Ed. Weber (1850), are not now used, as
the results obtained are not sufficiently accurate.

Method Of Welcker (1854). Begin by taking the weight of the animal to be
experimented on ; place a cannula in the carotid, and allow the blood to run
into a flask previously weighed, and in which small pebbles (or Hg) have been
placed in order to detibrinate the blood by shaking. Take a part of this deiibrin-
ated blood, and make it cherry-red in colour by passing through it a stream of CO

NORMAL QUANTITY OF BLOOD. 61

(because ordinary blood varies in colour according to the amount of contained in
it Gscheidlen, Heidenhain). Tie a \~ -shaped cannula in the two cut ends of the
carotid, and allow a 0'6 per cent, solution of common salt to flow into the vessel
from a pressure bottle ; collect the coloured fluid issuing from the jugular veins
and inferior vena cava until the fluid is quite clear. The entire body is then
chopped up (with the exception of the contents of the stomach and intestines,
which are weighed, and their weight deducted from the body-weight), and
extracted with water, and after twenty-four hours the fluid is expressed. This
water, as well as the washings with salt solution, are collected and weighed, and
part of the mixture is saturated with CO. A sample of this dilute blood is placed
in a vessel with parallel sides (1 c.m. thick), opposite the light (the so-called
hsematinometer), and in a second vessel of the same dimensions, a sample of the
undiluted CO-blood is diluted with water from a burette until both fluids give
the same intensity of colour. From the quantity of water required to dilute the
blood to the tint of the washings of the blood-vessels, the quantity of blood in
the washings is calculated. (On chopping up the muscles aloue, we obtain the
amount of Hb present in them, which is not taken into calculation Kuhne).

Quantity of Blood in Various Animals. The quantity of blood in
the mouse = T V to T V; guinea-pig 1 *-..- (^ T to -oV) ', rabbit = ^
( l_ to ^V) ; dog = T '^ (tV to -L-) ; cat = ST.V ; birds = -^ to -V ;

\ 1 5 ;:-/" O 13X11 1 8 / 3 2103 10 13'

frog =r T V to ^j ; fishes = yj to JL of the body-weight (without the
contents of the stomach and intestines).

The specific gravity of the blood ought always to be taken when
estimating the amount of blood. The amount of blood is diminished
during inanition ; fat persons have relatively less blood ; after haemorr-
hage the loss is at first replaced by a watery fluid, while the blood-
corpuscles are gradually regenerated (p. 63).

The estimation of the quantify of blood in different organs is done by
suddenly ligaturing their blood-vessels intra vitam. A watery extract
of the chopped up organ is prepared, and the quantity of blood estimated
as described above. Roughly, it may be said that the lungs, heart, large
arteries, and veins contain ; the muscles of the skeleton, ; the
liver, : and other organs, ^ (Ranke).

41. Variations from the Normal Condition of

the Blood.

(A.) Increase of the Blood, or of its Individual Constituents. (l.) An

increase in the entire mass of the blood, uniformly in all organs, constitutes
polyamia (or plethora), and in over-nourished individuals it may approach a patho-
logical condition. A bluish-red colour of the skin, swollen veins, large arteries,
hard full pulse, injection of the capillaries and smaller vessels of the visible
mucous membranes are signs of this state, accompanied by congestion of the brain,
giving rise to vertigo, and congestion of the lungs, as shown by breathlessness.
After major amputations with little loss of blood a relative increase of blood has
been found (?) (plethora apocoptica).

Transfusion. Poly^mia may be produced artificially by the injection of blood
of the same species. If the normal quantity of blood be increased 83 per cent.

62 TRANSFUSION OF BLOOD.

no abnormal condition occurs, because the blood-pressure is not permanently
raised. The excess of blood is accommodated in the greatly distended capillaries,
which may be stretched beyond their normal elasticity (Worm Miiller). If it be
increased to 150 per cent, there are variations in the blood-pressure, life is
endangered, and there may be sudden rupture of blood-vessels (Worm Miiller).

Fate of Transfused Blood. After the transfusion of blood the formation of
lymph is greatly increased ; but in one to two days the serum is used up, the
water is excreted chiefly by the urine, and the albumin is partly changed into
urea (Landois). Hence, the blood at this time appears to be relatively richer in
blood-corpuscles (Panum, Lesser, Worm Miiller). The red corpuscles break up
much more slowly, and the products thereof are partly excreted as urea and partly
(but not constantly) as bile pigments. Even after a month an increase of
coloured blood-corpuscles has been observed (Tschirjew). That the blood-cor-
puscles are broken up sloiuly in the economy is proved by the fact that the amount
of urea is much larger when the same quantity of blood is swallowed by the
animal, than when an equal amount is transfused (Tschirjew, Landois). In the
latter case there is a moderate increase of the urea lasting for days, a proof of
the slow decomposition of the red corpuscles. Pronounced over-filling of the
vessels causes loss of appetite, and a tendency to haemorrhage of the mucous
membranes.

(-) PolySBlnia serosais that condition in which the amount of serum i.e.,
the amount of water in the blood, is increased. This may be produced artificially
by the transfusion of blood-serum from the same species. The water is soon given
off in the urine, and the albumin is decomposed into urea, without however, pass-
ing into the urine. An animal forms more urea in a short time from a quantity of
transfused serum than from the same quantity of blood, a proof that the blood-
corpuscles remain longer undecomposed than the serum (Forster, Landois). If
serum from another species of animal be used (e.g., dog's serum transfused into a
rabbit), the blood-corpuscles of the recipient are dissolved ; hremoglobinuria is
produced (Ponfick) ; and if there be general dissolution of the corpuscles, death
may occur (Landois).

PolySBmia aqUOSa is a simple increase of the water of the blood, and occurs
temporarily after copious drinking, but increased diuresis soon restores the normal
condition. Diseases of the kidneys, which destroy their secreting parenchyma,
produce this condition, and often general dropsy, owing to the passage of water
into the tissues. Ligature of the ureter produces a watery condition of the
blood.

(3.) Plethora poiycythaemica, Hypergloblllie. An increase of the red cor-
puscles has been assumed to occur when customary regular haemorrhages are inter-
rupted e.g. , menstruation, bleeding from the nose, &c. ; but the increase of corpuscles
has not been definitely proved. There is a proved case of temporary polycytha;mia
viz., when similar blood is transfused, a part of the fluid is used up, while the
corpuscles remain unchanged for a considerable time. There is a remarkable increase
in the number of blood-corpuscles (to S'82 millions per cubic millimetre, p. 4) in
certain severe cardiac affections where there is great congestion, and much water
transudes through the vessels. In cases of hemiplegia, for the same reason, the
number of corpuscles is greater on the paralysed congested side (Penzoldt). After
diarrhoea, which diminishes the water of the blood, there is also an increase
(Brouardel). There is a temporary increase in the luzmatoblasts as a reparative
process after severe haemorrhage (p. 15), or after acute diseases. In cachectic
conditions this increase continues, owing to the diminished non-conversion of these
corpuscles into red corpuscles. In the last stages of cachexia the number
diminishes more and more until the formation of hwmatoblasts ceases (Hayem).

(4.) Plethora hyperalbuminosa is a term applied to the increase of albumins in
the plasma, such as occurs after taking a large amount of food. A similar con-

ABNORMAL CONDITIONS OF THE BLOOD. (i,3

dition is produced by transfusing the serum of the same species, whereby, at the
same time, the urea is increased. Injection of egg-albumin produces albuminuria
(Stokes, Lehmann).

(B.) Diminution of the Quantity of Blood, or its Individual Consti-
tuents. (1.) Oligaemia VCra, or diminution of the quantity of blood as a whole,
occurs whenever there is haemorrhage. Life is endangered in newly -born children
when they lose a few ounces of blood; in children a year old, on losing half-a-pound ;
and in adults, when one-half of the total blood is lost. Women bear loss of blood
much better than men. The periodical formation of blood after each menstruation
seems to enable blood to by renewed more rapidly in their case. Stout persons,
old people, and children do not bear the loss of blood well. The more rapidly
blood is lost, the more dangerous it is.

Symptoms Of LOSS Of Blood. Great loss of blood is accompanied by general
paleness and coldness of the cutaneous surface, increased oppression, twitching of
the eyeballs, noises in the ears and vertigo, loss of voice, great breathlessness,
stoppage of secretions, coma ; dilatation of the pupils, involuntary evacuations of
urine and fteces, and lastly, general convulsions, are sure signs of death b;/
hcemorrhage. In the gravest cases restitution is only possible by means of trans-
fusion. Animals can bear the loss of one-fourth of their entire blood without the
blood-pressure in the arteries permanently falling, because the blood-vessels con-
tract and accommodate themselves to the smaller quantity of blood (in consequence
of the stimulation of the vasomotor centre in the medulla). The loss of one-third
of the total blood diminishes the blood-pressure considerably (one-fourth in the
carotid of the dog). If the haemorrhage is not such as to cause death, the fluid
part of the blood and the dissolved salts are restored by absorption from the
tissues, the blood-pressure gradually rises, and then the albumin is restored,
though a longer time is required for the formation of red corpuscles. At first,
therefore, the blood is abnormally rich in water (hydrcemia), and at last abnormally
poor in corpuscles (oligocytlicemia, hypocjlobulie). With the increased lymph-
stream which pours into the blood, the colourless corpuscles are considerably
increased above normal, and during the period of restitution fewer red corpuscles
seem to be used up (^.;/., for bile).

After moderate bleeding from an artery in animals, Buntzen observed that the
volume of the blood was restored in several hours; after more severe haemorrhage
in 24 to 48 hours. The red blood-corpuscles after a loss of blood equal to
I'l to 4 '4 per cent, of the body-weight, are restored only after 7 to 34 days.
The generation begins after 24 hours. During the period of regeneration the
number of the smallest blood-corpuscles (hsemato-blasts) is increased. Even in
man the duration of the period of regeneration depends upon the amount of blood
lost (Lyon). The amount of haemoglobin is diminished nearly in proportion to
the amount of the haemorrhage (Bizzozero and Salvioli).

Metabolism in Anasmia. The condition of the metabolism within the bodies of
anasmic persons is important. The decomposition of proteids is increased (the
same is the case in hunger), hence the excretion of urea is increased (Bauer,
Jiirgensen). The decomposition of fats, on the contrary, is diminished, which
stands in relation with the diminution of C0 2 given off. Anaemic and chlorotic
persons put on fat easily. The fattening of cattle is aided by occasional bleedings
and by intercurrent periods of hunger (Aristotle).

(2.) An excessive thickening of the blood through loss of water is called
01ig8Binia Sicca. This occurs in man after copious watery evacuations, as in
cholera, so that the thick tarry blood stagnates in the vessels. Perhaps a similar
condition though to a less degree may exist after very copious perspiration.

(3.) If the proteids in blood be abnormally diminished the condition is called
Oligsemia hypalbuminosa ; they may be diminished about one-half. They
are usually replaced by an excess of water in the blood. Loss of albumin from

64 ABNORMAL CONDITIONS OF THE BLOOD.

the blood is caused directly by albuminuria ('25 grammes of albumin may be given off
by the urine daily), persistent suppuration, great loss of milk, extensive cutaneous
ulceration, albuminous diarrhoea (dysentery). Frequent and copious haemorrhages,
however, by increasing the absorption of water into the vessels, at first produce
oligajmia hypalbuminosa.

Mellitaemia. The suar in the blood is partly given off by the urine, and in
"diabetes mellitus " one kilo. ('2 - 2 Ibs.) may be given off daily, when the quantity
of urine may rise to 25 kilos. To replace this loss a large amount of food and
drink is required, whereby the urea may be increased threefold. The increased
production of sugar causes an increased decomposition of albuminous tissues; hence
the urea is always increased, even though the supply of albumin be insufficient.
The patient loses flesh ; all the glands, and even the testicles, atrophy or degenerate
(pulmonary phthisis is common); the skin and bones become thinner; the
nervous system holds out longest. The teeth become carious on account of the acid
saliva, the crystalline lens becomes turbid from the amount of sugar in the fluid
of the eye which extracts water from the lens (Kunde, Heubel), and wounds heal
badly because of the abnormal condition of the blood. Absence of all carbo-
hydrates in the food causes a diminution of the sugar in the blood, but does not
cause it to disappear entirely. An excessive amount of inosite has been found in the
blood and urine, constituting mellituria inoslta (Vohl).

Lipseniia, or an Increase of the Fat in the Blood, occurs after every meal

rich in fat, so that the serum may become turbid like milk. Pathologically, this
occurs in a high degree in drunkards and in corpulent individuals. When there is
great decomposition of albumin in the body (and therefore in very severe diseases),
the fat in the blood increases, and this also takes place after a liberal supply of
easily decomposable carbo-hydrates and much fat.

The Salts remain very persistently in the blood. The withdrawal of common
salt produces albuminuria, and, if all salts be withheld, paralytic phenomena occur
(Forster). Over -feeding with salted food, such as salt meat, has caused death
through fatty degeneration of the tissues, especially of the glands. Withdrawal of
lime and phosphoric acid produces atrophy and softening of the bones. In infectious
diseases and dropsies the salts of the blood are often increased, and diminished in
inflammation and cholera. [NaCl is absent from the urine in certain stages of
pneumonia, and it is a good sign when the chlorides begin to return to the
urine].

The amount Of fibrin is increased in inflammations of the lung and pleura;
hence, such blood forms a crusta pldo'j'istica (p. 39). In other diseases, where
decomposition of the blood-corpuscles occurs, the fibrin is increased, perhaps
because the dissolved red corpuscles yield material for the formation of fibrin.
After repeated hpernorrhages, Signi. Mayer found an increase of fibrin. Blood rich
in fibrin is said to coagulate more tsloivly than when less fibrin is present still
there are many exceptions.

For the abnormal changes of the red and white blood-corpuscles see p. 23.

Physiology of the Circulation,

42. General View of the Circulation.

THE blood within the vessels is in a state of
carried from the ventricles by the large
arteries (aorta and pulmonary) and their
branches to the system of capillary vessels,
from which again, it passes into the veins
that end in the atria of the auricles (W.
Harvey).

The cause of the circulation is the differ-
ence of pressure which exists between the
blood in the aorta and pulmonary artery on
the one hand, and the two venae cavse and
the four pulmonary veins on the other.
The blood, of course, moves continually in
its closed tubular system in the direction of
least resistance. The greater the difference
of pressure, the more rapid the movement
will be. The cessation of the difference of
pressure (as after death) naturally brings the
movement to a standstill. The circulation
is usually divided into

(1.) The greater, or systemic circulation,
which includes the course of the blood from
the left auricle and left ventricle, through the
aorta and all its branches, the capillaries of
the body and the veins, until the two vense
cavoa terminate in the right auricle.

('!.} The lesser, or pulmonic circulation,
which includes the course from the right
auricle and right ventricle, the pulmonary
artery, the pulmonary capillaries, and the
four pulmonary veins springing from them,
until these open into the right auricle.

(3.) The portal circulation, which is some-
times spoken of as a special circulatory system,
although it represents only a second set of
capillaries (within the liver) introduced into

continual motion, being
K

L

J- 16-

of the c
right auricle ; A, right ven-
tricle ; l>, left auricle ; B,
left ventricle ; 1, pulmonary
artery ; 2, aorta with semi-
lunar valves ; I, area of pul-
monary circulation; K,area
of systemic circulation in
region supplying the supe-
i-ior vena cava, o; G, area
supplying the inferior vena
cava, u; d, d, intestine; m,
mesenteric artery; q, portal
vein; L, liver; /i, hepatic
vein.

the course of a venous
5

6G

MUSCULAR FIBRES OF THE HEART.

trunk. It consists of the vena portarum formed by the union of the
intestinal or mesenteric and splenic veins, and it passes into the
liver, where it divides into capillaries, from which the hepatic veins
arise. These last veins join the inferior vena cava.

Strictly speaking, however, there is no special portal circulation.
Similar arrangements occur in other animals in different places
e.g., snakes have such a system in their supra-renal capsules, and the
frog in its kidneys.

When an artery splits up into fine branches during its course, and
these branches do not form capillaries, but reunite into an arterial
trunk, a rete mirabilc is formed, such as occurs in apes and the eden-
tata. Similar arrangements may exist on veins, giving rise to venous
retici mirabilia.

43. The Heart

Muscular Fibres of the Heart. The musculature of the mammalian
heart consists of short (50 to 70 //, man), very fine, transversely striated
muscular fibres, which are actual uni-cellular elements (Eberth), devoid
of a sarcolemma (15 to 25 ^ broad), and usually divided at their
blunt ends, by which means they anastomose and form a net-
Avork. (Fig. 17, A, B.) The individual muscle-cells contain in their

A

C

Fio;. 17.

A, branched muscular fibres from the heart of a mammal ; B, transverse section of
the cardiac fibres ; b, connective tissue corpuscles ; c, capillaries ; C, muscular
fibres from the heart of a frog.

centre an oval nucleus, and are held together by a cement which is
blackened by silver nitrate, and dissolved by a 33 per cent, solution of
caustic potash. This cement is also dissolved by a 40 per cent, solu-
tion of nitric acid. The transverse strine are not very distinct, and
not unfrequently there is an appearance of longitudinal striation, pro-
duced by a number of very small granules arranged in rows within

ARRANGEMENT OF THE CARDIAC MUSCULAR FIBRES. 67

the fibres. The fibres are gathered lengthwise in bundles, or fasciculi,
surrounded and separated from each other by delicate processes of the
perimysium. When the connective tissue is dissolved by prolonged
boiling, these bundles can be isolated, and constitute the so-called
" fibres " of the heart. The transverse sections of the bundles in
the auricles are polygonal or rounded, while in the ventricles they
are somewhat flattened. [The muscular mass of the heart is called the
myocardium, and is invested by fibrous tissue. It is important to
notice that the connective tissue of the visceral pericardium (epicardiuvi)
is continuous with that of the endocardium by means of the peri-
mysium surrounding the bundles of muscular fibres.] The fine spaces
which exist between these bundles form narrow lacunse, lined with
epithelium, and constituting part of the lymphatic system of the heart.

[The cardiac muscular fibres occupy an intermediate position between striped
and plain muscular fibres. Although they are striped they are invohintary, not
being directly under the influence of the will, while they contract more slowly
than a voluntary muscle of the skeleton.]

[In the/ror/'s heart the muscular fibres are in shape elongated spindles, or fusi-
form, in this respect resembling the plain muscle-cells, but they are transversely
striped (Fig. 17, C). They are easily isolated by means of a 33 per cent, solution of
potash or dilute alcohol (Weissmann, Ranvier).]

44. Arrangement of the Cardiac Muscular Fibres,
and their Physiological Importance.

The study of the embryonic heart is the key to a proper understand-
ing of the complicated arrangement of the fibres in the adult heart.
The simple tubular heart of the embryo has an outer circular and an
inner longitudinal layer of fibres. The septum is formed later ; hence,
it is clear that a part, at least, of the fibres must be common to the
two auricles, and a part also to the two ventricles, since there is,
originally, but one chamber in the heart. The muscular fibres of the
auricles are, however, completely separated from those of the ventricles
by the fibro-cartilaginous rings. In the auricles the fundamental
arrangement of the embryonic fibres partly remains, while in the
ventricles it becomes obscured as these cavities undergo a sac-like
dilatation, and also become twisted in a spiral manner.

(1.) The Muscular Fibres of the Auricles are completely separated
from the fibres of the ventricles by the fibrous rings which surround
the auriculo-ventricular orifices, and which serve as an attachment for
the auriculo-ventricular valves (Fig. 18, I). The auricles are much
thinner than the ventricles, and their fibres are generally arranged in
two layers ; the outer transverse layer is continuous over both auricles,

G8

ARRANGEMENT OF THE CARDIAC MUSCULAR FIBRES.

whilst the inner one is directed longitudinally. The outer transverse
fibres may be traced from the openings of the venous trunks anteriorly
and posteriorly over the auricular walls. The longitudinal fibres are
specially well marked where they are inserted into the fibro-cartila-
ginous rings, while in some parts of the anterior auricular wall they
are not continuous. In the auricular septum, some fibres, circularly
disposed around the fossa ovalis (formerly the embryonic opening of the
foramen ovale) are well marked. Circular bands of striped muscle exist
around the veins where they open into the heart; these are least
marked on the inferior vena cava, and are stronger and reach higher
(2'5 cm.) on the superior vena cava (Fig. 18, II). Similar fibres exist
around the four pulmonary veins, where they join the left auricle, and
these fibres (which are arranged as an inner circular and an outer
longitudinal layer) can be traced to the hilus of the lung in man and
some mammals ; in the ape and rat they extend on the pulmonary veins
right into the lung. In the mouse and bat, again, the striped muscular
fibres pass so far into the lungs that the walls of the smaller veins are
largely composed of striped muscle (Stieda).

v.p

Fig. 18.

I. Course of the muscular fibres on the left auricle Observe the outer transverse
and inner longitudinal fibres, the circular fibres on the pulmonary veins (v, p)\
V, the left ventricle (John Reid). II. Arrangement of the striped muscular
fibres on the superior vena cava (Elischer) o, opening of vena azygos ;
v, auricle.

Circular muscular fibres are found where the vena magna cordis
enters the heart, and in the valvula thelesii which guards it.

From a pliy 'siological point of view the following facts are to be noted
as a result of the anatomical arrangement :

(l.)'The auricles contract independently of the ventricles. This is
seen when the heart is about to die ; then there may be several
auricular contractions for one ventricular, and at last only the auricles

ARRANGEMENT OF THE VENTRICULAR FIBRE.v 69

pulsate. The auricular portion of the right auricle heats longest ;
hence, it is called the " ultinrum moriens." Independent rhythmical
contractions of the vense cavje and pulmonary veins are often noticed
after the heart has ceased to beat (Haller, Nysten). [This beating-
can also be observed in those veins in a rabbit after the heart is cut
out of the body.]

(2.) The double arrangement of the fibres (transverse and longi-
tudinal) produces a simultaneous and uniform diminution of the
auricular cavity (such as occurs in most of the hollow viscera).

(3.) The contraction of the circular muscular fibres around the
venous orifices, and the subsequent contraction of the auricle, cause
these veins to empty themselves into the auricle ; and by their presence
and action they prevent any large quantity of blood from passing back-
ward into the veins when the auricle contracts. [Xo valves are
present in the superior and inferior vena cava in the adult heart, or in
the pulmonary veins, hence the contraction of these. Circular muscular
fibres play an important part in preventing any reflux of blood during
the contraction of the auricles.]

45. Arrangement of the Ventricular Fibres.

(2.) The Muscular Fibres of the Ventricles. The fibres in the thick
wall of the ventricles are arranged in several layers (Fig. 19, A) under the
pericardium. First, there is an outer longitudinal layer (A) which is in
the form of single bundles on the right ventricle, but forms a complete
layer on the left ventricle, Avhere it measures about one'-eighth of
the thickness of the ventricular Avail. A second longitudinal layer of
fibres lies on the inner surface of the ventricles, distinctly visible at the
orifices, and within the vertically placed papillary muscles, whilst
elsewhere it is replaced by the irregularly arranged trabeculte carnese.
Between these two layers there lies the thickest layer, consisting of
more or less transversety-air&iiged bundles which may be broken up into
single layers more or less circularly disposed. The deep lympJitif/i-
vessels run between the layers, whilst the Uood-vessels lie within the
substance of the layers and are surrounded by the primitive bundles
of muscular fibres (Henle). All three layers are not completely
independent of each other; on the contrary, the fibres which run
obliquely form a gradual transition between the transverse layers and
the inner and outer longitudinal layers. It is not, however, quite
correct to assume that the outer longitudinal layer gradually passes
into the transverse, and this again into the inner longitudinal layer
(as is shown schematically in C) ; because, as Henle pointed out, the
transverse fibres are relatively far greater in amount. In general, the

70

ARRANGEMENT OF THE VENTRICULAR FIBRES.

Fig. 19.

Course of the ventricular muscular fibres A, On the anterior surface ; B, View
of the apex with the vortex (Henle); C, Scheme of the course of the
fibres within the ventricular wall ; D, Fibres passing into a papillary muscle
(C. Luclwig).

outer longitudinal fibres are so arranged as to cross the inner longi-
tudinal layer at an acute angle. The tranverse layers lying between
these two form gradual transitions between these directions. At the
apex of the left ventricle, the outer longitudinal fibres bend or curve
so as to meet at the so-called vortex (Wirbct) B, where they enter
the muscular substance, and, taking an upward and inward direction,
reach the papillary muscles, D (Lower) ; although it is a mistake to
say that all the bundles which ascend to the papillary muscles arise
from the vertical fibres of the outer surface : many seem to arise
independently within the ventricular wall. According to Henle,
all the external longitudinal fibres do not arise from the fibrous rings
or the roots of the arteries.

[The assumption that the muscles of the ventricle are arranged so as to form
a figure of 8, or in loops, seems to be incorrect ; thus, fibres are said to arise at the
base of the ventricle, to pass over it, and to reach the vortex, where they pass
into the interior of the muscular substance, to end either in the papillary muscles,
or high up on the inner surface of the heart at its base. Figs. C and D give a
schematic representation of this view.]

A special layer of circular muscular fibres, which acts like a true
sphincter, surrounds the arterial opening of the left ventricle, and
seems to have a certain independence of action (Henle).

PERICARDIUM, ENDOCARDIUM, VALVES.

71

Only the general arrangement of the ventricular muscular fibres has been
indicated here (Lower, Gasp. Wolff, 1780-92). C. Ludwig (1849), and more
recently Pettigrew (1864) have made the subject a special study, and followed out
its complications. According to the last observer, there are seven layers in the
ventricle, viz., three external, a fourth or central layer, and three internal. These
internal layers are continuous with the corresponding extenial layers at the apex,
thus one and seven, two and six.

46. Pericardium, Endocardium, Valves.

The PERICARDIUM encloses within its two layers [visceral and parietal] a lymph
space the pericardia! space which contains a small quantity of lymph the
pericardial fluid. It has the structure of a serous membrane, i.e., it consists of
connective tissue mixed vn.ila.fine elastic fibres arranged in the form of a thin delicate
membrane, and covered on its free surfaces with a single layer of epithelium or
endothelium, composed of irregular, polygonal, flat cells.

A rich lymphatic network lies under the pericardium (fig. 20) and endocardium
and also in the deeper layers of the visceral pericardium next the heart, but stomata
have not been found leading from
the pericardial cavity into these
lymphatics, nor do these open-
ings exist on the parietal layer.
[Salvioli has shown that lym-
phatic spaces also lie between
the muscular bundles.] Around
the coronary arteries of the heart
exist deposits of fat and lymph-
vessels (Wedl), which lie in the
furrows and grooves in the sub-
serosa of the epicardium (visceral
layer).

The ENDOCARDIUM (accordingto
Luschka) does not represent the
intiina alone, but the entire wall
of a blood-vessel. Next the cavity
of the heart, it consists of a

.

single layer of polygonal, flat,

Fig. 20.

Lymphatic of the pericardium epithelium stained
with nitrate of silver.

nucleated endothclial cells. [Under this there is a nearly homogeneous hyaline
layer (fig. 21, a), slightly thicker on the left side, which gives the endocardium its
polished appearance.] Then
follows, as the basis of the
membrane, a layer of fine elastic
fibres stronger in the auricles,
and in some places thereof as-
suming the characters of a
fenestrated membrane. Be-
tween these fibres a small
quantity of connective tissue
exists, which is in larger
amount and more areolar in its
characters next the myocar- Fig. 21.

dium. Bundles of non-striped Section of the endocardium a, hyaline layer ; //,
muscular fibres (few in the network of fine elastic fibres ; c, network of
auricles) are scattered and .stronger elastic fibres; d, myocardium with
arranged for the most part blood-vessels, which do not pass into the endo-
longitudmally between the cardium.

72 STRUCTURE OF THE VALVES.

clastic fibres. These seem evidently meant to resist the distension which is
.apt to occur when the heart contracts and great pressure is put upon the
endocardium. In all cases where high pressure is put upon walls composed of
soft parts, we always find muscular fibres present, and never elastic fibres alone.
No l>too<l-i;x.<i In occur in the endocardium (Langer).

The valves also belong to the endocardium both the sr.mi-lunur
of the aorta and pulmonary artery, which prevent the blood from passing
back into the ventricles, and the tricuspid (right auriculo-ventricular)
and mitral (left auriculo-ventricular), which protect the auricles from
the same result. The lower vertebrata have valves in the orifices of
the vense cavee which prevent regurgitation into them; while in birds
and some mammals these valves exist in a rudimentary condition.

The VALVES are fixed by means of their base to resistant fibrous
rings, consisting of elastic and fibrous tissue. They are formed of
two layers (1.) the fibrous, which is a direct continuation of the fibrous
rings, and (2.) a layer of clastic elements. The elastic layer of the
auriculo-ventricular valves is an immediate prolongation of the
endocardium of the auricles, and is directed towards the auricles.
The semi-lunar valves have a thin elastic layer directed towards the
arteries, which is thickest at their base. The connective-tissue layer
directed towards the ventricle is about half the thickness of the
valve itself.

Muscular Fibres in the Valves. The auriculo-ventricular valves
also contain striped muscular fibres (Reid, Gussenbauer). Radiating
fibres proceed from the auricles and pass into the valves, which, when
the atria contract, retract the valves towards their base, and thus make
a larger opening for the passage of the blood into the ventricles ; accord-
ing to Paladino, they raise the valves after they have been pressed
down by the blood-current. This observer also described some longi-
tudinal fibres which proceed from the ventricles to enter these valves.
There is also a concentric layer of fibres arranged near their point of
attachment, and directed more towards their ventricular surface.
These fibres seem to contract sphincter-like when the ventricle contracts,
and thus approximate the base of the valves, and so prevent too great
tension being put upon them. The larger chorda? tendinias also
contain striped muscle (Oehl), while a delicate muscular network
exists in the valvula thebesii and valvula eustachii.

Purkinje's Fibres. This name is applied to an anastomosing system of
grayish fibres which exist in the sub-endocardial tissue of the ventricles, especially
in the heart of the sheep and ox. The fibres are made up of polyhedral, clear cells,
containing some granular protoplasm, and usually two nuclei (Fig. 22). The
margins of the cells are striated. Transition forms are found between these cells
and the ordinary cardiac fibres ; in fact these cells become continuous with the
true fully developed cardiac fibres. They represent cells which have been arrested

SELF-STEERING ACTION OF THE HEART.

73

in their development. They are absent in man and the lower vertebrates, but in
birds and some mammals they are well marked (Schweigger-Seidel, Ranvier).
Blood -Vessels occur

in the auriculo-ventricular
valves only where mus-
cular fibres are present,
while the semi - lunar
valves are usually devoid
of vessels except at their
base. The best figures
of the blood-vessels of
the valves are given by
Langer. The network of
lymphatics in the en-
docardium reaches to-
wards the middle of
the valves (Eberth and
Belajeff).

Weight Of the Heart. Purkinje's fibres isolated with dilute alcohol c, cell ;
According to W. Miiller /, striated substance ; n, nucleus x 300.

the proportion between

the weight of the body and the heart in the child, and until the body reaches
40 kilos., is 5 grams, of heart-substance to 1 kilo, of body-weight; when the
body-weight is from 50 to 90 kilos., the ratio is 1 kilo, to 4 grams, of heart-
substance ; at 100 kilos. 3 '5 grams. As age advances, the auricles become
stronger. The right ventricle is half the weight of the left. The weight of the
heart of an adult man is about 9 oz. (1 oz. =29'2 grms.); female Si oz. (Clen-
dinning as a mean of 400 observations). [According to Laennec the heart is about
the size of the closed fist of the individual]. Blosfield and Dieberg give 34G grms.
for the male, and 310 to 340 grms. for the female heart. The specific gravity of
the heart-muscle is 1'069 (Kapff).

47. Self-Steering Action of the Heart.

Coronary Vessels. Many observations have been made to ascertain
whether the orifices of the coronary arteries are covered by the semi-
lunar valves during contraction of the left ventricle (Thebesius, 1739;
Briicke, 1854), or whether they are permanently open (Morgagni, 1723;
Hyrtl, 1855) Fig. 23.

Anatomical Investigations The two coronary arteries whose

branches do not anastomose (Hyrtl, Henle ; but this is denied by
Krause and L. Langer), arise from the beginning of the aorta in the
region of the sinus of Valsalva. The position of origin varies (1.)
either the origins lie within the sinus, or (2.) their openings are only
partially reached by the margins of the semi-lunar valves (which is
usually the case in the left coronary artery of man and the ox), or (3.)
their orifices lie clear above the margins of the valves. Post-mortem
observations seem to show that during contraction of the ventricle, it
is very improbable that the semi-lunar valves constantly cover the
origin of the coronary arteries.

74 SELF-STEERING ACTION OF THE HEART.

The Self-Steering Action of the Heart. Briicke attempted to show
that during the systole, or contraction of the ventricle, the semi-lunar
valves covered the openings of the coronary arteries, so that these
vessels could be filled with blood only during the diastole or relaxation
of the ventricle. To him it seemed that (a.) the diastolic filling of the
coronary arteries would help to dilate the ventricles ; (&.) on the con-
trary, a systolic filling of these arteries would oppose the contraction,
because the systolic filling and expulsion of the blood from the
coronary arteries would diminish the force of the ventricular contrac-
tion. To this arrangement, Briicke gave the above name.

Arguments against B^ucke's View. The following considei-ations militate
against this theory :(!.) Filling the coronary vessels under a high pressure in a
dead heart causes a diminution of the ventricular cavity (v. Wittich). (2.) The
chief trunks of the coronary arteries lie in loose sub-pericardia! fatty tissue, in the
cardiac sulci, hence a dilatation of the ventricle through this agency is most
unlikely (Landois). (3.) Experiments on animals have shown that a coronary
artery spouts, like all arteries, during the systole of the ventricle. Von Ziemssen
found that in the case of a woman (Serafin), who had a large part of the anterior
wall of the thorax removed by an operation, the heart being covered only by a
thin membrane, the pulse in the coronary arteries was synchronous with the
pulse in the pulmonary artery. H. N. Martin and Sedgwick placed a manometer
in connection with the coronary artery, and another with the carotid in a large
dog, and they found that the pulsations occurred simultaneously. When a coronary
artery is divided, the blood flows out continuously, but undergoes acceleration during
the systole of the ventricles (Endemann, Perls). (4.) If a strong intermittent
current of water be allowed to flow through a sufficiently wide tube into the left
auricle of a fresh pig's heart, so that the water passes into the aorta, and if the aorta
be provided with a vertical tube, the water flows continuously from the coronary
arteries, and is accelerated during the systole. (5.) It is exceedingly improbable
that the coronary arteries should be tilled during the diastole while all the other
arteries are filled during systole of the ventricle. (6.) There is always a sufficient
quantity of blood in the sinus of Valsalva to fill the arteries during the first part of
the systole. (7. ) The valves, when raised, are not applied directly to the aortic
wall (Hamberger, Eiidinger) even by the most energetic pressure from the ventricle
(Sandborg and Worm Miiller). (8.) Observations on voluntary muscles have shown
that the small arteries dilate during contraction of the muscle, and the blood
stream is accelerated. (9.) By the systolic filling of the aorta the arterial path is
elongated this elastic distension is compensated before the diastole occurs. By
the recoil of the aortic walls the layer of blood in them is driven backwards and
closes the valves (Ceraclini). According to Sandborg and Worm Miiller, the semi-
lunar valves close just after the ventricles have begun to relax, which agrees with
the curve obtained from the cardiac impulse (Fig. 25a, A).

During the systole, the small arterial trunks lying next the ventricu-
lar cavities have to bear a higher pressure than that borne by the
aorta, and their lumen must be compressed during the systole so that
their contents are propelled towards the veins.

Peculiarities of the Cardiac Blood- Vessels. The capillary vessels of the

myocardium are very numerous, corresponding to the energetic activity of the

LIGATURE OF THE CORONARY ARTERIES. 75

heart. Where they pass into veins, several unite at once to form a thick venous
trunk whereby an easy passage is offered to the blood. The veins are provided
with valves so that (1.) during systole of the right auricle the venous stream is
interrupted; (2.) during contraction of the ventricles the blood in the coronary
veins is similarly accelerated as in the veins of muscles.

The coronary arteries are characterised by their very thick connective tissue and
elastic intima, which perhaps accounts for the frequent occurrence of atheroma of
these vessels (Henle). Some observers (Hyrtl and Henle) maintain that the
coronary arteries do not anastomose, but this is denied by Langer and Krause.
Many of the small lower vertebrates have no blood-vessels in their heart-muscle,
e.g., frog (Hyrtl).

Coronary Circulation. The phenomena produced by partial oblitera-
tion or ligature of the coronary arteries are most important. In man
analogous conditions occur, as in atheroma or calcification of these
arteries.

Ligature of the Coronary Arteries. See and others ligatured the
coronary arteries in a dog, and found that after 2 minutes the cardiac
contractions gave place to twitchings of the muscular fibres, and
ultimately the heart ceased to beat. Ligature of the anterior
coronary artery alone, or of both its branches, is sufficient to produce
this result.

If the coronary arteries be compressed or tied in a rabbit in the
angle between the bulbus aortse and the ventricle, the heart's action is
soon weakened, owing to the sudden anaemia and to the retention of
the decomposition products of the metabolism in the heart-muscle (v.
Bezold, Erichsen). Ligature of one artery first affects the corresponding
ventricle, then the other ventricle, and, last of all, the auricles. Hence,
compression of the left coronary artery (with simultaneous artificial
respiration in a curarised animal) causes slowing of the contractions,
especially of the left ventricle, whilst the right one at first contracts
more quickly and then, gradually, its rhythm is slowed. The contrac-
tions of the left ventricle are not only slowed but also weakened,
whilst the right pulsates with undiminished force. Hence it follows
that as the left half of the heart cannot expel the blood in suffi-
cient quantity, the left auricle becomes filled, whilst the right
ventricle, not being affected, pumps blood into the lungs. (Edema of
the lungs is produced by the high pressure in the pulmonary circula-
tion, which is propagated from the right heart through the pulmonary
vessels into the left auricle (Samuelson and Griinhagen).

According to Sig. Mayer, protracted dyspnoea causes the left ventricle
to beat more feebly sooner than the right, so that the left side of the
heart becomes congested. Perhaps this may explain the occurrence
of pulmonary oedema during the death agony.

Cohnheim and v. Schulthess-Rechberg found after ligature of one of the large
branches of a coronary artery in a large dog, that at the end of a minute the

7fi THE MOVEMENTS OF THE HEART.

pulsations become discontinuous; several, as it were, do not occur. This inter-
mittence becomes more pronounced, the two sides of the heart do not contract
simultaneously (arltythmia), the heart beats more slowly, and the blood-pressure
falls. Suddenly, about 103 sees, after the ligature is applied, both ventricles cease
to beat, and there is the greatest fall of the blood-pressure. After 10 to 20 sees.,
twitching movements occur in the ventricles, while the auricles pulsate regularly,
and may continue to do so for many minutes, while the ventricles cease to beat
altogether after 50 sees. According to Lukjanow, there is a peristaltic condi-
tion which operates upwards and downwards, and occurs in the period between
the regular contraction and the twitching vibratory movement.

48. The Movements of the Heart.

Cardiac Revolution. The movement of the heart is characterised by
an alternate contraction and relaxation of the cardiac walls. The
total cardiac movement is called a " CARDIAC REVOLUTION," or a
" cardiac cycle," and consists of three acts the contraction or systole
of the auricles, the contraction or systole of the ventricles, and the pause.
During the pause the auricles and ventricles are relaxed ; during the
contraction of the auricles the ventricles are at rest ; whilst during
the contraction of the ventricles, the auricles are relaxed. The rest
during the phase of relaxation is called the diastole. The following
is the sequence of events in the heart during a cardiac revolution :

EVENTS DURING A CARDIAC REVOLUTION.

(A.) The Blood Flows into the Auricles, and thus distends them and
the auricular appendages. This is caused by

(1.) The pressure of the blood in the venae cavae (right side) and the
pulmonary veins (left side) being greater than the pressure in the
auricles.

(2.) The clastic traction of the lungs ( 60) which, after complete
systole of the auricles, pulls asunder the now relaxed and yielding
auricular walls. The auricular appendages are also filled at the
same time, and they act to a certain extent as accessory reservoirs
for the large supply of blood streaming into the auricles.

(B.) The Auricles Contract, and we observe in rapid succession

(1.) The contraction and emptying of the auricular appendix
towards the atrium. Simultaneously the mouths of the veins become
narrowed (Haller, Nysten) owing to the contraction of their circular
muscular fibres (more especially the superior vena cava and the
pulmonary veins).

(2.) The auricular walls contract simultaneously towards the auriculo-
ventricular valves and the venous orifices, whereby

EVENTS DURING A CARDIAC CYCLE.

77

(3.) The blood is driven into the relaxed ventricles, which are con-
siderably distended thereby.

The contraction of the auricles is followed by

(a.) A slight stagnation of the blood in the large venous trunks, as
can be easily observed in a rabbit after division of the pectoral muscles
so as to expose the junction of the jugular Avith the subclavian vein.
There is no proper regurgitation of the blood, but only a partial
interruption of the inflow into the auricles, because, as already men-
tioned, the mouths of the veins are contracted, and because the
pressure in the superior vena cava and in the pulmonary veins soon
holds in equilibrium any reflux of blood; and lastly, because any reflux

Gypsum cast of the ventricles of the human heart viewed from behind and above;
the walls have been removed, and only the fibrous rings and the auriculo-
ventricular valves are retained L, left, R, right ventricle ; S, position of
septum; F, left fibrous ring, with mitral valve closed; D, right fibrous ring,
with tricuspid closed ; A, aorta, with the left (Ci) and right (C) coronary
arteries ; S, siuus of valsalva ; P, pulmonary artery.

78 EVENTS DURING A CARDIAC CYCLE.

into the cardiac veins is prevented by valves. The movement of the
heart causes a regular pulsatile phenomenon in the blood of the vense
cavoe, which under abormal circumstances may produce a venous pulse
(see Venous pulse).

(&.) The chief motor effect of the contraction of the auricles is the
dilatation of the relaxed ventricle, which has already been dilated to a
slight extent by the elastic force of the lungs.

The dilatation of the ventricles has been ascribed to the elasticity of the
muscular walls the strongly contracted ventricular walls (like a compressed india-
rubber bag), in virtue of their elasticity, are supposed to return to their normal
resting form, and thereby to suck in or aspirate the blood under a negative pres-
sure. Such suction power on the part of the ventricle is, however, only effective
to a very slight extent.

(c.) When the ventricles are distended by the inflowing blood, the
auriculo-ventricular valves are floated up, partly by the recoil or
reflexion of the blood from the ventricular wall, and partly owing to
their lighter specific gravity, whereby they easily float into a more or
less horizontal position. The valves are also raised to a slight extent
by the longitudinal muscular fibres, which pass from the auricles into
the cusps of the valve (Paladino).

(C.) The Ventricles now Contract, and simultaneously the auricles
relax, whereby

(1.) The muscular walls contract forcibly from all sides, and thus
diminish the ventricular cavity.

(2.) The blood is at once pressed against the under-surface of the
auriculo-ventricular valves, whose curved margins are opposed to each
other like teeth, and are pressed hermetically against each other (Sand-
borg and Worm Miiller). It is impossible for the blood to push the
cusps backwards into the auricle, as the chordce tendinice hold fast their
margins and surfaces like a taut sail. The margins of the neighbouring

cusps are also kept in apposition by the
chordre tendinise from one papillary muscle
always passing to the adjoining edges of
two cusps (John Eeid). The extent to
which the ventricular wall is shortened is
compensated by the contraction of the
papillary muscle, and also of the large
muscular chordte, so that the cusps cannot
be pushed into the auricle.

24 ' When the valves are closed their surfaces

The closed semi-lunar are horizontal, so that even when the
valves of the pulmonary ventricles are contracted to their greatest
artery seen from below. extentj ft gmall amount o f Uood remains,

which is not expelled (Sandborg and Worm Miiller).

PATHOLOGICAL DISTURBANCES OF CARDIAC ACTION. 79

(3.) Opening of the Semi-lunar Valves. When the pressure within
the ventricle exceeds that in the arteries, the semi-lunar valves are
forced open and stretched like a sail across the pocket-like sinus,
without, however, being firmly or directly applied to the wall of the
arteries (pulmonary and aorta), and thus the blood enters the arteries.

Negative Pressure in the Ventricle. Goltz and Gaule found that there was
a negative pressure of 23 "5 mm. Hg. (dog) in the interior of the ventricle during a
certain phase of the heart's action. They surmised that that phase coincided with
the diastolic dilatation, for which they assumed a considerable power of aspiration.
Marey observed a similar condition and called it " vacuite postsystolique," but
thought that it coincided with the end of the systole; while Moens is of opinion that
this negative pressure within the ventricle obtains shortly lie/ore the. systole has
reached its height, i.e., just before the inner surface of the ventricles and the
valves, after the blood is expelled, are nearly in apposition. He explains this
aspiration as being due to the formation of an empty space in the ventricle caused
by the energetic expulsion of the blood through the aorta and pulmonary artery.

(D.) Pause. As soon as the ventricular contraction ends, and the
ventricles begin to relax, the semi-lunar valves close. The diastole of
the ventricles is followed by the PAUSE. Under normal circumstances
the right and left halves of the heart always contract or relax uni-
formly and simultaneously.

49. Pathological Disturbances of Cardiac Action.

Cardiac Hypertrophy. All RESISTANCES to the movement of the blood
through the various compartments of the heart, and through the vessels com-
municating with it, cause a greater amount of work to be thrown upon the
portion of the heart specially related to this part of the circulatory system ; con-
sequently, there is produced an increase in the thickness of the muscular walls
and dilatation of the heart. If the resistance or obstacle does not act upon
one part of the heart alone, but on parts lying in the onward direction of the
blood-stream, these parts also subsequently undergo hypertrophy. If in addi-
tion to the muscular thickening of a part of the heart the cavity is simultaneously
dilated, it is spoken of as eccentric hypertrophy or hypertrophy with dilatation.

The obstacles most likely to occur in the blood-vessels are narrowing of the
lumen or want of elasticity in their walls ; in the heart, narrowing of the arterial
or venous orifices or insufficiency or incompeteucy of the valves. Incompetency
of the valves forms an obstruction to the movement of the blood, by allowing
part of the blood to flow back or regurgitate, thus throwing extra work upon
the heart.

Thus arise (1.) Hypertrophy of the left ventricle, owing to resistance in the area
of the systemic circulation, especially in the arteries and capillaries not in the
veins. Amongst the causes are, constriction of the orifice or other parts of the
aorta, calcification, atheroma, and want of elasticity of the large arteries and
irregular dilatations in their course (Aneurisms) ; insufficiency of the aortic
valves, in which case the same pressure always obtain within the ventricle and in
the aorta ; and lastly, contraction of the kidneys, so that the excretion of water by
these organs is diminished. Even in mitral insufficiency compensatory hyper-
trophy of the left ventricle must occur, owing to the hypertrophy of the left atrium
in consequence of the increased blood-pressure in the pulmonary circuit.

80 III I] APEX-BEAT.

(2.) Hypertrophy of the Ivft auricle occurs in stenosis of the left auriculo-ven-
tricular orifice, or iu insufficiency of the mitral valve, and it occurs also as a result
of aortic insufficiency, because the auricle has to overcome the continual aortic
pressure within the ventricle.

(3.) Hypertrophy of the riyht ventricle, occurs (a. ) when there is resistance to
the blood-stream through the pulmonary circuit. The resistance may be due to
(.) obliteration of large vascular areas in consequence of destruction, shrinking or
compression of the lungs, and the disappearance of numerous capillaries in emphy-
sematous lungs. (jS.) Overfilling of the pulmonary circuit with blood in conse-
quence of stenosis of the left auriculo-ventricular orifice or mitral insufficiency
consequent upon hypertrophy of the left auricle resulting from aortic insufficiency.
(b. ) Hypertrophy of the right ventricle will also occur when the valves of the
pulmonary artery are insufficient, thus permitting the blood to flow back into the
ventricle, so that the pressure within the pulmonary artery prevails within the
right ventricle (very rare).

(4.) Hypertrophy of the rirjlit auricle occurs in consequence of the last-named
condition, and also from stenosis of the tricuspid orifice, or insufficiency of the
tricuspid valve (rare). If several lesions occur simultaneously, the result is
complex.

Artificial Injury to the Valves. 0. Rosenbach has made experiments on
the action of the heart when its valves are injured artificially. If the aortic valves
are perforated, with or without simultaneous injury to the mitral or tricuspid
valves, the heart does more work ; thus the physical defect is overcome for a time,
so that the blood-pressure does not fall. The heart seems to have a store of
reserve energy, which is called into play. Soon, however, dilatation takes place,
on account of the regurgitatiou of the blood into the heart. Hypertrophy then
occurs, but the compensation meanwhile must be obtained through the reserve
energy of the heart.

Impeded Diastole. Among causes which hinder the diastole of the heart are
copious effusions into the pericardium, or pressure of tumours upon the heart. The
systole is greatly interfered with when the heart is united to the pericardium and
to the connective tissue in the mediastinum. As a consequence the connective
tissue, and even the thoracic wall, are drawn in during contraction of the heart,
so that there is a retraction of the region of the apex-beat during systole, and a
protrusion of this part during the diastole.

50. The Apex-Beat The Cardiogram.

Cardiac Impulse. By the term " apex-beat" or cardiac impulse, is
understood under normal circumstances an elevation (perceptible to
touch and sight) in a circumscribed area of the fifth left intercostal
space, caused by the movement of the heart. [The apex-beat is felt in
the fifth left intercostal space, two inches below the nipple, and one
inch to its sternal side.] The impulse is more rarely felt in the fourth
intercostal space, and it is much less distinct when the heart beats
against the fifth rib itself. The position and force of the cardiac
impulse vary with changes in the position of the body.

[Methods. To obtain a curve of the apex-beat or a cardiogram, we may
use one or other of the following cardiographs (Fig. 25). Fig. 25, A, is the
first form used by Marey, and it consists of an oval wooden capsule applied in an

THE CARDIOGRAM.

81

air-tight manner over the apex-beat. The disc, p, capable of being regulated by the
screw, s, presses upon the region of the apex-beat, while t is a tube which may
be connected with a registering tambour (Fig. 28). B is an improved form of
the instrument, consisting essentially of a tambour, while attached to the mem-
brane is a button, p, to be applied over the apex-beat. The movements of the air
within the capsule are communicated by the tube, t, to a registering tambour. Fig.
25, C, is the pansphygmograph. of Brondgeest, which consists of a Marey's tam-
bour, in an iron horse-shoe frame, and adjustable by means of a screw, s. Burdon-
Sanderson's cardiograph is shown in D. The button, p, carried by the spring, e,
does not rest upon the caoutchouc membrane, but on an aluminium plate
attached to it. The apparatus is adjusted to the chest by three supports.
Fig. 25, E, shows a modified instrument on the same principle by Grunmach
and v. Knoll. In all these figures the t indicates the exit-tube communicating
with a registering tambour (Fig. 28). D and E may be used for other purposes,
e.y., for the pulse, so that they are polygraphs. See also Fig. 52.]

Fig. 25.

Various cardiographs A, original form as used by Marey; B, improved form by
Marey; C, Pansphygmograph of Brondgeest; D, Cardiograph of Burdon-
Sandersou ; E, that of Grunmach and v. Knoll.

Fig. 25a, A, shows the cardiogram or the impulse-curve of the heart of
a healthy man ; B, that of a dog, obtained by means of a sphygmo-
graph. In both the following points are to be noticed a, &, corre-
sponds to the time of the pause and the contraction of the auricles. As
the atria contract in the direction of the axis of the heart from
the right and above towards the left and below, the apex of the
heart moves towards the intercostal space. The two or three smaller

82

THE CARDIOGRAM.

Fig. 25.

Curves taken from the apex-beat A, normal curve from mau ; B, from a dog;
C, vei y rapid curve from a dog ; D and E, normal curves from a mau, regis-
tered on a vibrating glass-plate where eacli indentation = O'OIGIS sees. In
all the curves, a, //, means contraction of the auricles ; b, c, ventricular
systole ; </, closure of the aortic valves ; e, closure of the pulmonary artery
valves; e,f, relaxation or diastole of the ventricle.

elevations are perhaps caused by the contractions of the ends of the
veins, the auricular appendices, and the atria themselves.

.Some observers ascribe the small elevations occurring before b to the rilling of
the ventricle during the diastole, whereby it is pressed against the intercostal
space (Maurer, Griitzner).

The portion, l>, c, which communicates the greatest impulse to the
instrument, and also to one's hand when it is placed on the apex-
beat, is caused by the contraction of the ventricle, and during it the first
sound of the heart occurs. Frequently, but erroneously, the cardiac
impulse has been ascribed to this contraction of the ventricle. It
however, is due to all those conditions which cause an elevation in the
region of the apex -beat.

CAUSE OF THE CARDIAC IMPULSE.

83

The cause of the 'ventricular impulse has been much discussed. It
depends upon the following :

(1.) The base of the heart (auriculo-ventricular groove) represents
during diastole a transversely-placed ellipse, while during contraction it
has a more circular figure. Thus, the long diameter of the ellipse is
diminished in the cat from 28 to 22*5 mm. (C. Ludwig) ; the small
diameter is increased (^ to -4-), while the base is brought nearer to
the chest- wall (Arnold, Ludwig) Fig. 26, 1. This alone does not cause
the impulse, but the basis of the heart, being hardened during the
systole and brought nearer to the chest-wall, allows the apex to
execute the movement which causes the impulse.

(2.) During relaxation, the ventricle lies with its apex obliquely
downwards, and with its long axis in an oblique direction so that the
angles formed by the axis of the ventricles with the diameter of the
base are unequal represents a regular cone, with its axis at right angles
to its base. Hence, the apex must be erected from below and behind,
forwards and upwards (Harvey " cor sese erigere "), and when
hardened during systole presses itself into the intercostal space
(Ludwig) Fig. '20, II.

Fig. 26.

I, Schematic horizontal section through the heart and lungs, and the thoracic
walls, to show the change of shape which the base of the heart undergoes
during contraction of the ventricle 1, 2, transverse diameter of the ventricle
during diastole ; c, position of the thoracic wall during diastole ; a, b, trans-
verse diameter of the heart during systole, with e, the position of the anterior
thoracic wall during systole. II, Side-view of the heart s, apex during
diastole ; p, the same during systole (C. Ludwig).

84 CAUSE OF THE CARDIAC IMPULSE.

(3.) The ventricle undergoes during systole a slight spiral twisting
on its long axis ("lateralem inclinationem" Harvey), so that the apex
is brought from behind more forward, and thus a greater portion of the
left ventricle is turned to the front. This rotation is caused by the
muscular fibres of the ventricles, which proceed from that part of the
fibrous rings between the auricles and ventricles which lies next the
anterior thoracic wall. The fibres pass from above obliquely down-
wards, and to the left, and also run in part upon the posterior surface
of the ventricle. When they contract in the axis of their direction,
they tend to raise the apex, and also to bring more of the posterior
surface of the heart in relation with the anterior thoracic wall (Harvey,
Kiirschner, Wilckens). This rotation is favoured by the slightly spiral
arrangement of the aorta and pulmonary artery (Koruitzer).

These are the most important causes, but minor causes are as
follows :

(4.) The " reaction impulse " is that movement which the ventricles
are said to undergo (like an exploded gun or rocket) at the moment
when the blood is discharged into the aorta and pulmonary artery,
whereby the apex goes in the opposite direction i.e., downwards and
slightly outwards (Alderson 1825, Gutbrod, Skoda, Hiffelsheim).
Landois, however, has shown that the mass of blood is discharged into
the vessels 0'08 of a second after the beginning of the systole, while
the cardiac impulse occurs with the first sound.

(5.) When the blood is discharged into the aorta and pulmonary
artery, these vessels are slightly elongated, owing to the increased blood -
pressure (Senac). As the heart is suspended from above by these
vessels, the apex is pressed slightly downwards and forwards towards
the intercostal space (?)

Guttmann and Jahn observed that the cardiac impulse disappeared after sudden
ligature of the aorta and pulmonary artery, while Chauveau and Eosensteiu
maintain that it persists.

As the cardiac impulse is observed in the empty hearts of dead
animals, (4) and (5) are certainly of only second-rate importance. Filehne
and Pentzoldt maintain that the apex during systole does not move to
the left and downwards, as must be the case in (4) and (5), but that it
moves upwards and to the right a result corroborated by v. Ziemssen,
which, however, is disputed by Losch.

It is to be remembered that as the apex is always applied to the chest- wall,
separated from it merely by the thin margin of the lung, it only presses
against the intercostal space during systole (Kiwisch).

After the apex of the curve, c, has been reached at the end of the

THE TIME OCCUPIED BY THE CARDIAC MOVEMENTS. 85

systole, the curve falls rapidly, as the ventricle rapidly becomes relaxed.
In the descending part of the curve, at d and e, are two elevations,
which occur simultaneously with the second sound. These are caused by
the sudden closure of the semi-lunar valves, which, occurring suddenly,
is propagated through the axis of the ventricle to its apex, and thus
causes a vibration of the intercostal space; d corresponds to the
closure of the aortic valves, and e to the closure of the piilmonary
valves. The closure of the valves in these two vessels is not simul-
taneous, but is separated by an interval of 0'05 to 0'09 sec. The
aortic valves close sooner on account of the greater blood-pressure
there (Landois, 1876, Ott and Haas, Malbranc, Maurer, Griitzner,
Langendorff, v. Ziemssen, and Ter Gregorianz).

Complete diastolic relaxation of the ventricle occurs from c to / in
the curve. It is clear, then, that the cardiac impulse is caused chiefly
by the contraction of the ventricles, while the auricular systole and the
vibration caused by the closure of the semi-lunar valves are also con-
cerned in its production.

51. The Time Occupied by the Cardiac

Movements.

Methods. The time occupied by the various phases of the movements of the
heart may be determined by studying the apex-beat curve.

(1.) If we know at what rate the plate on which the curve was obtained moved
during the experiment, of course all that is necessary is to measure the distance,
and so calculate the time occupied by any event (see Pulse).

(2.) It is preferable, however, to cause a tuning-fork, whose rate of vibration
is known, to write its vibrations under the curve of the apex-beat, or the
curve may be written upon a plate attached to a vibrating tuning-fork (Fig.
25a, D, E). Such a curve contains fine teeth, caused by the vibrations of the
tuning-fork. D and E are curves obtained from the cardiac impulse in this way
from healthy students. In D the notch d, is not indicated. Each complete
vibration of the tuning-fork, reckoned from apex to apex of the teeth = 0'01613
sec., so that it is simply necessary to count the number of teeth and multiply to
obtain the time. The values obtained vary within certain limits even in health.

Pause and Contraction of Auricles. The value of a b = pause + con-
traction of the auricles is subject to the greatest variation, and depends
chiefly upon the number of heart-beats per minute. The more quickly
the heart beats, the smaller is the pause, and conversely. In some
curves, even when the heart beats slowly, it is scarcely possible to
distinguish the auricular contraction (indicated by a rise) from the
part of the curve corresponding to the pause (indicated by a horizontal
line). In one case (heart-beats 55 per minute) the pause = 0'4 sec., the
auricular contraction = (H77 sec. In Fig. 25, A, the time occupied by
the pause + the auricular contraction (74 beats per minute) = 0'5 sec.

80 TIME OCCUPIED BY THE VENTRICULAR SYSTOLE,

In D the a ft = 19 to 20 vibrations = 0'3 2 sec.; in E= 26 vibrations
= 0-42 sec.

Ventricular Systole. The ventricular systole is calculated from the
beginning of the contraction, ft to e, when the semi-lunar valves are
closed ; it lasts from the first to the second sound. It also varies
somewhat, but is more constant. When the heart beats rapidly, it is
somewhat less during slow action, greater. In E = - 32 sec.; in D
= 0'29 sec. ; with 55 beats per minute Landois found it = 0*34, with a
very high rate of beating = 0'199 sec.

When the ventricle beats feebly, it contracts more slowly, as can be shown by
applying the registering apparatus to the heart of an animal just killed. In Fig.
27, from the ventricle of a rabbit just killed, the slow heart-beats, B, ai-e seen to
last longest.

Fig. 27.

Curves obtained from the ventricle of a rabbit, and written upon a vibrating plate
attached to a tuning-fork (vibration '01613 sec.) A, tolerably] soon after
death ; B, from the dying ventricle.

In calculating the time occupied by the ventricular systole we must remember
(1.) The time between the two sounds of the heart, i.e., from the beginning of the
first to the end of the second sound (fc to e). (2.) The time the Hood flows into the
aorta, which comes to an end at the depression between c and r? (in Fig. 25a, E).
Its commencement, however, does not coincide with b, as the aortic valves open
O'OSS (Landois) to 0'073 (Rive) sec. after the beginning of the ventricular systole.
Hence the aortic current lasts O'OS to 0'09 sec.

This is calculated in the following way : The time between the first sound of
the heart and the pulse in the axillary artery is 0'137 sec., and of this time 0'052
sec. are occupied in the propagation of the pulse-wave along the 30 cm. of artery
lying between the root of the aorta and the axilla. Thus the pulse-wave in the
aorta occurs 0'137 minus 0'052 = 0'OS5 sec. after the beginning of the first sound.

The current in the pulmonary artery is interrupted in the depression between
d and c. (3.) Lastly, the time occupied by the muscular contraction of the
ventricle, which begins at b, reaches its greatest extent at c, and is completely
relaxed at/. The apex of the curve, <:, may be higher or lower according to the
flexibility of the intercostal space, hence the position of c varies. In hypertrophy
with dilatation of the left ventricle, the duration of the ventricular contraction
does not greatly exceed the normal.

The time which elapses between d and e, i.e., between the complete
closure of the aortic and pulmonary valves, is greater the more the
pressure in the aorta exceeds that in the pulmonary artery, as the

ENDOCARDIAL J'KKSM'KK.

valves are closed by the pressure from above, and the difference in
time may be 0'05 sec., or even double that time, in which case the
second sound appears double (compare p. 94). If the aortic pressure
diminishes while that in the pulmonary artery rises, d and e may
be so near each other that they are no longer marked as distinct
elements in the curve.

The time, e,f, during which the ventricle relaxes varies somewhat:
O'l sec. may be taken as a mean.

Accelerated Cardiac Action. When the action of the heai-t is greatly
accelerated, the pause is considerably shortened in the first instance (Bonders),
and to a less extent the time of contraction of the auricles and ventricles. When
the pulse-rate is very rapid, the systole of the atria coincides with the closure of
the arterial valves of the preceding contraction, as is shown in Fig. 25, C (dog).

In registering the cardiac impulse, the apparatus is separated by a greater or
less extent of soft parts from the heart itself, so that in all cases the intercostal
tissues do not follow exactly the movements of the heart, and thus the curve
obtained may not coincide mathematically with the movements of the heart. It
is desirable that curves be obtained froai persons whose hearts are exposed, -i.e.,
in cases of ectopia cordis.

Gibson inscribed cardiograms from the heart of a man with cleft sternum.
The following were the results obtained: Auricular contraction = O'l 15; ventri-
cular contraction (t>,d) = 0"2S ; difference between closure of valves (r/, r) = 0'09
ventricular diastole (<?,/) O'll ; pa use = '45 sec.

Endocardial Pressure. In large mammals, such as the horse,
Chauveau and Marey determined
the duration of the events that
occur within the heart, and also
the endocardial pressure, by
means of a cardiac sound. Small
elastic bags attached to tubes
were introduced through the
jugular vein into the right auricle
and ventricle. Each of these
tubes was connected with a regis-
tering tambour (Fig. 28), and
simultaneous tracings of the varia-
tions of pressure within the cavi- Marey 's registering tambour, consisting of

Fi. 28.

ties of the heart were obtained
by causing the writing-points of
the levers of the tambours to
write upon a revolving cylinder.

a metallic capsule, T, with thin india-
rubber stretched over it, and bearing
an aluminium disc, which acts upon
the writing lever, H. By means of a
thick-walled caoutchouc tube, it may
be connected with any system con-
taining air, so as to record variations
of pressure.

Fig. 29, A, gives the result obtained
when the elastic bag was placed in
the right aiiricle, introduced through
the jugular vein and superior vena cava; B, when it was pushed through the
tricuspid valve into the right ventricle ; D, in the root of the aorta, pushed in

KNPOCARDTAL PRESSURE.

through the carotid ; 0, pushed past the semi-lunar valves into the left ventricle ;
while at E a similar bag has been placed externally between the heart's apex
and the inner wall of the chest. In all cases v = auricular contraction; V, that of
the ventricle ; <?, closure of semi-lunar valves, sooner in C than B; P = pause.

Method. The cardiac sound consists of a tube containing two separate air-
passages, and in connection with each of these there is a small elastic bag or
.ampulla. One of the bags is fixed to the free end of the sound, and communicates
with one of the air-passages. The other bag is placed in connection with the
second air-passage in the sound, and at such a distance, that, when the former bag
lies within the ventricle, the latter is in the auricle. Each bag and air-tube in
connection with it, is connected with a Marey's tambour, Fig. 28, provided with a
lever which inscribes its movements upon a revolving cylinder. Any variation
of pressure within the auricle or ventricle will affect the elastic ampulla?, and thus
raise or depress the lever. Care must be taken that the writing-points of the
levers, are placed exactly above each other. A tracing of the cardiac impulse is
taken simultaneously by means of a cardiograph attached to a separate tambour.

It has still to be determined whether the auricles and ventricles act
alternately, so that at the moment of the beginning of the ventricular

Eight Auricle.

Bight Ventricle.

Left Ventricle.

Aorta.

"Cardiac Impulse.

Fig. 29.
Curves obtained from the heart by the cardiac sound (Chauveau and Marey).

PATHOLOGICAL DISTURBANCES OF THE CARDIAC IMPULSE. 89

contraction the auricles relax, or whether the ventricles are contracted
while the auricles still remain slightly contracted, so that the whole
heart is contracted for a short time at least. The latter view was
supported by Harvey, Bonders, Schiflf, and others, while Haller and
many of the more recent observers support the view that the action of
the auricles and ventricles alternates. In the case of Frau Serafin,
whose heart was exposed, v. Ziemssen and Ter Gregorianz obtained
curves from the auricles, which showed that the contraction of the
auricles continued even after the commencement of the ventricular
systole. In Marey's curve (Fig. 29) the contraction of the ventricle is
represented as following that of the auricle.

52. Pathological Disturbances of the Cardiac

Impulse.

Change in the Position of the Apex-beat. The position of the cardiac

impulse is changed (1) by the accumulation of fluids (serum, pus, blood) or gas
in one pleural cavity. A copious effusion into the left pleural cavity compresses
the lung, and may displace the heart towards the right side, while effusion on the
right side may push the heart more to the left. As the right heart must make
a greater effort to propel the blood through the compressed lung, the cardiac
impulse is usually increased. Advanced emphysema of the lung, causing the
diaphragm to be pressed downwards, displaces the heart downwards and inwards,
while conversely the pushing or pulling up of the diaphragm (by contraction of
the lung, or through pressure from below) causes the apex-beat to be displaced
upwards (even to the third intercostal space), and also slightly to the left.
Thickening of the muscular walls and dilatation of the cavities (hypertrophy with
dilatation) of the left ventricle make that ventricle longer and broader, while the
increased cardiac impulse may be felt to the left of the mammary line, and
in the axillary line in the sixth, seventh, or even eighth intercostal space.
Hypertrophy, with dilatation of the right side, increases the breadth of the heart,
while the cardiac impulse is felt more to the right, even to the right of the
sternum, and at the same time it may be slightly beyond the left mammary
line. In the rare cases where the heart is transposed, the apex-beat is felt on
the right side. When the cardiac impulse goes to the left of the left mammary
line, or to the right of the parastemal line, the heart is increased in breadth, and
there is hypertrophy of the heart. A greatly increased cardiac impulse may
extend to several intercostal spaces.

The cardiac impulse is abnormally weakened during atrophy and degeneration
of the cardiac muscle, or by weakening of the innervation of the cardiac ganglia.
It is also weakened when the heart is separated from the chest-wall owing to the
collection of fluids or air in the pericardium, or by a greatly distended left lung ;
and, indeed, when the left side of the chest is filled with fluid, the cardiac impulse
may be extinguished. The same occurs when the left ventricle is very imperfectly
filled during its contraction (in consequence of marked narrowing of the mitral
orifice), or when it can only empty itself very slowly and gradually, as during
marked narrowing of the aortic orifice.

An increase of the cardiac impulse occurs during hypertrophy of the walls, as
well as after the influence of various stimuli (psychical, inflammatory, febrile,
toxic) which affect the cardiac ganglia. Great hypertrophy of the left ventricle

00

VARIATIONS OF TIFK rARITAC IMlTl.si:.

causes the heart to heave, so that a part of the left chest-wall may be raised and
also vibrate during systole.

A falling in of the anterior wall of the chest during cardiac systole occurs in the
third and fourth interspaces, not tmfrequently under normal circumstances,
sometimes during increased cardiac action, and in eccentric hypertrophy of the ven-
tricles. As the heart's apex is slightly displaced, and the ventricle becomes slightly
smaller during its systole, the empty space is rilled by the yielding soft parts of
the intercostal space. When the heart is united with the pericardium and the
surrounding connective tissue, which renders systolic locomotion of the heart
impossible, a falling in of the chest-wall during systole takes the place of the
cardiac impulse (Skoda). During the diastole a diastolic cardiac impulse of the
corresponding part of the chest- wall may be said to occur.

Changes in the cardiac impulse are best ascertained by taking graphic repre-
sentations of the cardiac impulse, and studying the curves so obtained. This
method has been largely followed by many clinicians.

In all the following curves, <Y, />, means auricular contraction ; J>, c, ventricular

Fig. 30.

Various forms of curves obtained from the cardiac impulse a, b, Contraction of
|^ auricles ? b, c, ventricular systole; d, closure of aortic, and 'e of pulmonary
valves ; e, f, diastole of ventricle ; P, Q, hypertrophy and dilatation of the
left ventricle ; E, stenosis of the aortic orifice ; F, mitral insufficiency ; G,
mitral stenosis ; L, nervous palpitation in Baseclow's disease ; M, case of
so-called hemisystole.

THE HEART-SOUNDS. 01

contraction; d, closure of the aortic valves, and e of the pulmonary; c, /, the
time the ventricle is relaxed (Fig. 30.)

In curve P (much reduced), taken from a case of marked hypertrophy with,
dilatation, the ventricular contraction, 6 c, is usually very great, while the time
occupied by the contraction is not much increased. P and Q were obtained from
a man suffering from marked eccentric hypertrophy of the left ventricle, in con-
sequence of insufficiency of the aortic valves. Curve Q was taken intentionally
over the auriculo-ventricular groove, where a falling in of the chest-wall occurred
during systole ; nevertheless, the individual events occurring in the heart are
indicated.

Fig. E is from a case of aortic stenoxitt. The auricular contraction (a, b) lasts
only a short time ; the ventricular systole is obviously lengthened, and after a
short elevation (b, c) shows a series of fine indentations (c, e) caused by the blood
being pressed through the narrowed and roughened aorta.

Fig. F, from a case of insufficiency of the mitral valve, shows (a, b) well marked
on account of the increased activity of the left auricle, while the shock (d) from
the closure of the aortic valves is small on account of the diminished tension in
the arterial system. On the other hand, the shock from the accentuated pul-
monary sound (P) is very great, and is in the apex of the curve. On account of
the great tension in the pulmonary artery, the second pulmonary tone may be so
strong, and succeed the second aortic sound (d) so rapidly, that both almost merge
completely into each other (H and K).

The curve of stenosis of the mitral orifice (G) shows a long irregular notched
auricular contraction (a, b) caused by the blood being forced through an irregular
narrow orifice. The ventricular contraction (b, c) is feeble on account of its being
imperfectly tilled. The closures of the two valves, d and c, are relatively far apart,
and one can hear distinctly a reduplicated second sound. The aortic valves close
rapidly because the aorta is imperfectly supplied with blood, while the more
copious inflow of blood into the pulmonary artery causes a later contraction of its
valves (Geigel).

If the heart beats rapidly and feebly if the blood -pressure in the aorta and
pulmonary artery be low, the signs of closure of the pulmonary valves may be
absent as in curve L taken from a girl suffering from nervous palpitation and
inorbus Basedowii.

In very rare cases of insufficiency of the mitral valve, it has been observed that
at certain times both ventricles contract simultaneously, as in a normal heart, but
that this alternates with a condition where the right ventricle alone seems to con-
tract. Curve M is such a curve obtained by Malbranc, who called this condition
intermittent hemisystole. The first curve (I) is like a normal curve, during which
the whole heart acted as usual. The curve II, however, is caused by the right
side of the heart alone ; it wants the closure of the aortic valves, d, and there was
no pulse in the arteries. Owing to insufficiency of the tricuspid valve, the same
person had a venous pulse with every cardiac impulse, so that the arterial and
venous pulses first occurred together, and then the venous pulse alone occurred.

In these cases (Skoda, v. Bamberger, Leyden) the mitral insufficiency leads to
overflowing of the right ventricle, while the left is nearly empty, so that the right
side requires to contract more energetically than the left. It does not seem that
the right ventricle alone contracts in these cases, but rather that the action of the
left side is very feeble.

53. The Heart-Sounds.

On listening over the region of the heart in a healthy man, either
with the ear applied directly to the chest-wall, or by means of a

02 THE HEART-SOUND?!.

stethoscope (Laennec, 1819), we hear two characteristic sounds, the
so-called " heart-sounds." Harvey was acquainted with these sounds,
but they have been more carefully studied by clinicians since the time
of Laennec.

The first sound [long or systolic] is somewhat duller, longer, and
one-third or one-fourth deeper, than the second sound; it is less sharply
defined at first, and is isochronous with the systole of the ventricles (TurnerJ.
The second sound [short or diastolic] is clearer, sharper, shorter, more
sudden, and is one-third to one-fourth higher ; it is sharply defined and
isochronous with the closure of the semi-lunar valves. There is a very
short interval between the first and second sounds, and between the
second and the next following first sound a distinctly longer interval.
This is the pause.

[The sounds emitted during each cardiac cycle have been compared
to the pronunciation of the syllables lubb, dtip. We may express the
course of events with reference to the sounds, thus: lubb, dup, pause.]
Or the result may be expressed thus

V V

Bu - fup. Bu - tup.

The causes of the first sound are due to two conditions. As^the
sound is heard in an excised heart in which the movements of the
valves are arrested, and also when the finger is introduced into the
auriculo-ventricular orifices so as to prevent the closure of the valves
(C. Ludwig and Dogiel), one of the chief factors lies in the " muscle-
sound " produced by the contracting muscular fibres of the ventricles
(Williams, 1835).

This sound is supported and increased by the sound produced by the
tension and vibration of the auriculo-ventricular valves and their
chordre tendiniae, at the moment of the ventricular systole (Rouanet,
Kiwisch, Bayer, Giese).

Wintrich, by means of proper resonators, has been able so to analyse
the first sound as to distinguish the clear, short, valvular part from the
deep, long, muscular sound.

The muscle-sound produced by transversely-striped muscle does not occur with a
simple contraction, but only when several contractions are superposed to produce
tetanus (see Muscle). The ventricular contraction is only a simple contraction,
but it lasts considerably longer than the contraction of other muscles, and herein
lies the cause of the occurrence of the muscle-sound during the ventricular con-
traction.

Defective Heart-Sounds. In certain conditions (typhus, fatty degeneration
of the heart) where the muscular substance of the heart is much weakened, the

THE HEART-SOUNDS.

93

Fig. 31.

The heart its several parts arid great vessels in relation to the front of the
thorax. The lungs are collapsed to their normal extent, as after death,
exposing the heart. The outlines of the several parts of the heart are indi-
cated by very fine dotted lines. The area of propagation of valvular murmurs
is marked out by more visible dotted lines. A, the circle of mitral murmur,
corresponds to the left apex. The broad and somewhat diffused area, roughly
triangular, is the region of tricuspid murmurs, and corresponds generally with
the right ventricle, where it is least covered by lung. The letter C is in its
centre. The circumscribed circular area, D, is the part over which the puluionic
arterial murmurs are commonly heard loudest. In many cases it is an inch,
or even' more, lower down, corresponding to the conus arteriosus of the right
ventricle, where it touches the walls of the thorax. The internal organs and
parts of organs are indicated by letters as follows r. au, right auricle,
traced in fine dotting ; ao, arch of aorta, seen in the first intercostal space,
and traced in fine dotting on the sternum ; vi, the two innominate veins ;
rv, right ventricle ; Iv, left ventricle.

94. CAUSES OF THE HEART-SOUNDS.

lirst sound may be completely inaudible. In aortic insufficiency, in which, in con-
sequence of the reflux of blood from the aorta into the ventricle, the mitral valve
is gradually stretched, and sometimes even before the beginning of the ventricular
systole, the first sound may be absent. Both pathological cases show that for the
production of the iirst sound, muscle-sound and valve-sound must eventually
work together, and that the tone is altered, or may even disappear, when one of
these causes is absent.

The Cause of the Second Sound is undoubtedly due to the prompt
closure, and therefore sudden stretching or tension, of the semi-lunar
valves of the aorta and pulmonary artery, so that it is purely a valvular
sound (Carswell and Rouanet, 1830). Perhaps it is augmented by the
sudden vibration of the fluid-particles in the large arterial trunks. As
already pointed out (p. 85), the aortic and pulmonary valves do not
close simultaneously. Usually, however, the difference in time is so
small that loth valves make one sound, but the second sound may be
double or divided when, through increase of the difference of pressure
in the aorta and pulmonary artery, the interval becomes longer. Even
in health this may be the case, as occurs at the end of inspiration or
the beginning of expiration (v. Dusch).

[The second sound has all the characters of a valvular sound. That
the aortic valves are concerned in its production, is proved by intro-
ducing a curved wire through the left carotid artery and hooking up
one or more segments of the valve, when the sound is modified, and it
may be replaced by an abnormal sound or " murmur." Again, when
these valves are diseased, the sound is altered, and it may be accompanied
or even displaced by murmurs.]

Where the Sounds are Heard Loudest. The sound produced by the
trinizpid ralce is heard loudest at the insertion of the fifth right rib into
the sternum, and from here somewhat inwards and obliquely upwards
along the sternum; as the mitral valve lies more to the left and deeper
in the chest, and is covered in front by the arterial orifice, the mitral
sound is best heard at the apex-beat, or immediately above it, where a
strip of the left ventricle lies next the chest-wall. [The sound is con-
ducted to the part nearest the ear of the listener by the muscular
substance of the heart.] The aortic and pulmonary orifices lie so
close together that it is convenient to listen for the second (aortic)
sound in the direction of the aorta and where it comes nearest to
the surface, i.e., over the first right costal cartilage close to its
junction with the sternum. The sound, although produced at the
semi-lunar valves, is carried upwards by the column of. blood and
by the walls of the aorta.

The sound produced by the pulmonary artery is heard most distinctly
in the second left intercostal space, somewhat to the left and external
to the margin of the sternum (Fig. 31).

\ T ARIATIONS Otf THE HEART-SOUNDS. 95

54. Variations of the Heart-Sounds.

An increase of the first sound of both ventricles indicates a more energetic con-
traction of the ventricular muscle and a simultaneously greater and more sudden
tension of the auriculo- ventricular valves. An increase of the second sound is a
sign of increased tension in the interior of the corresponding large arteries.
Hence, increase of the second (pulmonary) sound indicates overfilling and excessive
tension in the pulmonary circuit.

Feeble weak action of the heart, us well as abnormal want of blood in the heart,
causes weak heart-sounds, which is the case in degenerations of the heart-muscle.

Irregularities in structure of the individual valves may cause the heart-sounds
to become "impure." If a pathological cavity, filled with air, be so placed, and
of such a form as to act as a resonator to the heart-sounds, they may assume a
"metallic"' character. The first and second sounds may be "reduplicated" or
"divided." The reduplication of the lirst sound is explained by the tension
of the tricuspid and that of the mitral valves not occurring simultaneously.
Sometimes a sound is produced by a hypertrophied auricle producing an audible
presystolic sound, i.e., a sound or " murmur, 7 ' preceding the first sound. As the
aortic and pulmonary valves do not close quite simultaneously, a reduplicated
second sound is only an increase of a physiological condition (Landois). All con-
ditions which cause the aortic valves to close rapidly (diminished amount of blood
in the left ventricle) and the pulmonary valves to close later (congestion of the
right ventricle both conditions together in mitral stenosis), favour the production
of a reduplicated second sound.

Cardiac Murmurs. If irregularities occur in the valves, either in cases of stenosis
or in insufficiency, so that the blood is subjected to vibratory oscillations and friction,
then, instead of the heart-sounds, other sounds arise or accompany these murmurs
or bruits, which, when combined, are always accompanied by disturbances of the
circulation. It is rare that tumours ur other deposits projecting into the ventricles
cause murmurs, unless there be present at the same time lesions of the valves and
disturbances of the circulation. The cardiac murmurs or bruits are always related
to the systole or diastole, and usually the systolic are more accentuated and
louder. Sometimes they are so loud that the thorax trembles under their irregular
oscillations (fremitus, fremissement cataire).

In cases where dlastoltc murmurs are heard, there are always anatomical changes
in the cardiac mechanism. These are insufficiency of the arterial valves, or stenosis
of the auriculo-ventricular orifices (usually the left). Systolir murmurs do
not always necessitate a disturbance in the cardiac mechanism. They may
occur in the left side, owing to insufficiency of the mitral valve, stenosis of
the aorta, and in calcification and dilatation of the ascending part of the aorta.
These murmurs occur very much less frequently on the right side, and are due to
insufficiency of the tricuspid and stenosis of the pulmonary orifice.

Systolic murmurs often occur without any valvular lesion, although they are
always less loud, and are caused by abnormal vibrations of the valves or arterial
walls. They occur most frequently at the orifice of the pulmonary artery, less
frequently at the mitral, and still less frequently at the aorta or the tricuspid
orifice. Anaemia, general mal-nutrition, acute febrile affections, are the causes of
these murmurs.

Murmurs also occur during a certain stage of inflammation of the pericardium
(pericarditis) from the roughened surfaces of this membrane rubbing upon each
other. Audible friction- sounds are thus produced, and the vibration may even be
perceptible to touch. [These are "friction-sounds," and quite distinct from sounds
produced within the heart itself.]

9G DURATION OF THE MOVEMENTS OF THE HEART.

55. Duration of the Movements of the Heart.

That the heart continues to beat for some time after it is cut out
of the body, was known to Cleanthes, a contemporary of Herophilus,
300 B.C. The movement lasts longer in cold-blooded animals (frog,
turtle, fish) extending even to days than in mammals. A rabbit's heart
beats from 3 minutes up to 36 minutes after it is cut out of the body.
The average of many experiments is about 1 1 minutes. Panum found
the last trace of contraction to occur in the right auricle (rabbit)
15 hours after death ; in a mouse's heart, 46 hours; in a dog's, 96 hours.
An excised frog's heart beats, at the longest, 2| days (Valentin). In
a human embryo (third month) the heart was found beating after
4 hours. In this condition stimulation causes an increase and accelera-
tion of the action. Afterwards, the ventricular contraction first becomes
weaker, and soon each auricular contraction is not followed by a
ventricular contraction, two or more of the former being succeeded by
only one of the latter. At the same time the ventricles contract more
slowly (Fig. 27), and soon stop altogether, while the auricles still con-
tinue to beat. If the ventricles be stimulated directly, as by pricking
them with a pin, they may execute a contraction. The left auricle
soon ceases to beat, while the right auricle still continues to contract.
The right auricular appendage continues to beat longest, as was
observed by Galen and Cardan us (1550). The term " ultimum
moriens " is applied to it. Similar observations have been made upon
the hearts of persons who have been executed.

If the heart has ceased to beat, it may be excited to contract for a
short time by direct stimulation (Harvey), more especially by heat ;
even under these circumstances, the auricles and their appendages are
the last parts to cease contracting. As a general rule, direct stimula-
tion, although it may cause the heart to act more vigorously for a
short time, brings it to rest sooner. In such cases, therefore, the
regular sequence of events ceases, and there is usually a twitching
movement of the muscular fibres of the heart. C. Ludwig found that
even after the excitability is extinguished in the mammalian heart, it
may be restored by injecting arterial blood into the coronary arteries:
lesion of these vessels is followed by enfeebled action of the heart
(p. 75). Hammer found that in a man, whose left coronary artery was
plugged, the pulse fell from 80 to 8 beats per minute.

Action of Gases on the Heart. During its activity the heart uses
0, and produces CO.,, so that it beats longest in pure (12 hours)
(Castell), and not so long in N, H (1 hour) C0 2 (10 minutes), CO
(42 minutes) Cl (2 minutes), or in a vacuum (20 to 30 minutes)
(Boyle, 1670; Fontana, Tiedemann, 1847), even when there is watery

THE CARDIAC NERVES. 97

vapour present to prevent evaporation. If the heart be re-introduced
into it begins to beat again. [An excised heart suspended in
ordinary air beats three to four times as long as a heart which is
placed upon a glass-plate.] A heart which has ceased to contract
spontaneously may contract when an electrical stimulus is applied to
it, but it does not do so for a longer time than other muscles (Budge).

56, Innervation of the Heart.

[When the heart is removed from the body, or when all the nerves
which pass to it are divided, it still beats for some time, so that its
movements must depend upon some mechanism situated within itself.
The ordinary rhythmical movements of the heart are undoubtedly
associated with the presence of nerve ganglia, which exist in the
substance of the heart the intracardiac ganglia. But the movements
of the heart are influenced by nervous impulses which reach it from
Avithout, so that there falls to be studied an intracardiac and an extra-
cardiac nervous mechanism.]

57. The Cardiac Nerves.

The cardiac plexus is composed of the following nerves (1.) The
cardiac branches of the vagus, the branch of the same name from the
external branch of the superior laryngeal, a branch from the inferior
laryngeal, and sometimes branches from the pulmonary plexus of the
vagus (more numerous on the right side). (2.) The superior, middle,
inferior, and lowest cardiac branches of the three cervical ganglia and
the first thoracic ganglia of the sympathetic. (3.) The inconstant
twig of the descending branch of the hypoglossal nerve, which,
according to Luschka, arises from the upper cervical ganglia. From
the plexus there proceed the deep and the superficial nerves (the
latter usually at the division of the pulmonary artery under the arch of
the aorta, and containing a ganglion). The following nerves may be
separately traced from the plexus

(.) The plexus coronarius dexter and sinister (Scarpa), which con-
tains the vaso-motor nerves for these vessels (physiological proof still
wanting) as well as the nerves (sensory?) proceeding from them (to
the pericardium ?)

(5.) Intra-cardiac Nerves and Ganglia. The nerves lying in the
grooves of the heart and in its substance, containing numerous ganglia
(Remak), which are regarded as the automatic motor centres of the
heart. A nervous ring containing numerous ganglia corresponds to the
margin of the septum atriorum; there is another in the auriculo-
ventricular groove. Where the two meet, they exchange fibres. The
ganglia usually lie near the pericardium. In mammals the two largest

98

MOTOR CENTRES OF THE HEART.

ganglia lie near tho orifice of the superior vena cava in birds the
largest ganglion (containing thousands of ganglionic cells) lies pos-
teriorly where the longitudinal and transverse sulci cross each other.
Fine branches, also provided with small ganglia, proceed from these
ganglia, and penetrate the muscular walls of the auricles and ventricles.
Nerves of the Frog's Heart. In the frog there is a large ganglion
(EemaJc's) near the fibres of the vagus within the wall of the sinus
venosus. Branches of the vagus proceed from this ganglion along the an-
terior and posterior walls of the auricular septum, and each of these con-
tains a ganglion in the auriculo-ventricular groove, these aggregations
of ganglion cells constituting Bidder's ganglion. Fine branches proceed
from this ganglion, but they can be traced only for a short distance, so
that the greater part of the ventricle appears to be devoid of nerves.

According to Opeuchowsky, every part of the heart (frog, triton, tortoise) con-
tains nerve-fibres which are connected with every muscular fibre. In the auricles,
at the end of the non-medullated fibre, a tri-radiate nucleus exists which gives off
fibrils to the muscular bundles.

There is a network of fine nerve-fibres distributed immediately under the endo-
cardium these fibres act partly in a centripetal direction on the cardiac ganglia,
and are partly motor for the endocardial muscles. The parietal layer of the peri-
cardium contains (sensory) nerve-fibres. The following kinds of nerve-cells are found
unipolar cells, the single processes of which afterwards divide ; bipolar cells (Fig.
31a), which in the frog possess a straight (n) and usually also a spiral process (o).

58. The Automatic Motor Centres of the Heart.

(1.) We must assume that the nervous centres which excite the
cardiac movements, and maintain the rhythm of these movements, lie

within the heart, and that they are probably
represented by the ganglia.

(2.) There are not one, but several, of these
centres in the heart, which are connected with
each other by conducting paths. As long as
the heart is intact, all its parts are made to
move in rhythmical sequence from a principal
central point, an impulse being conducted
from this centre through the conducting paths
(Bonders). What the "discharging forces"
of these regular progressive movements are, is
unknown. If, however, the heart be subjected
to the action of diffuse stimuli (e.g., strong
Fig. 31a. electrical currents), all the. centres are thrown

Pyriforna ganglionic bi- into ti d spasm _iik e action of the heart
polar nerve-cell from
the heart of a frog occurs. The dominating centre lies 'in the

ifstrafght processf S^ mri des, hence the regular progressive move-
spiral process. ment usually starts from them. If the excit-

MOTOR CENTRES OF THE HEART. 99

ability is diminished (e.g., by touching the septum with opium
Ludwig, Hoffa), other centres seem to undertake this function, in
which case the movement may extend from the ventricles to the
auricles. If a heart be cut into pieces, so that the individual pieces
still remain connected with each other, the regular peristaltic or
wave-like movements proceeding from the auricles to the ventricle,
may continue for a long time (Donders, Engelmann). If the heart,
however, be completely divided into two distinct pieces (auricle and
ventricle), the movements of both parts continue, but not in the same
sequence they beat at different rates.

(3.) All stimuli of moderate strength applied directly to the heart
cause at first an increase of the rhythmical heart-beats ; stronger
stimuli cause a diminution, and it may be paralysis, which is often
preceded by a convulsive movement. Increased activity exhausts
the energy of the heart sooner.

(4.) The auricular centres seem to be more excitable than those of
the ventricle; hence, in a heart left to itself the auricles pulsate
longest.

(5.) The heart may be excited (reflexly) from its inner surface.
Weak stimuli applied to the inner surface of the heart greatly
accelerate the heart's action, the stimulus required being much
feebler than that applied to the external surface of the heart.
Strong stimuli, which bring the heart to rest, also act more easily when
applied to the inner surface than when they are applied to its outer
surface (Henry, 1832). The ventricle is always the part first to be
paralysed.

(6.) In order that the heart may continue to contract, it is necessary
that it be supplied with a fluid which in addition to (Ludwig, Volk-
mann, Goltz) must contain the necessary nutritive materials. The most
perfect fluid, of course, is blood. Hence the heart ceases to beat
in an indifferent fluid (O'G p.c. sodium chloride), but its activity may
be revived by supplying it with a proper nutritive fluid.

Cardiac Nutritive Fluids. These nutritive fluids are such as contain serum-
Lilbumin e.y., blood, serum, or lymph. Serum retains its nutritive properties
even after it has been subjected to diffusion (Martins and Kronecker). Milk and
whey (v. Ott), normal saline solution (O'G per cent. NaCl) mixed with blood,
albumin, or peptone, and 0'3 per cent, sodium carbonate (Kronecker, Merunowicz,
and Stienon), or a trace of caustic soda (Gaule), or a solution of the salts of
serum, are suitable.

(7.) The independent pulsations of parts of the heart which are
devoid of ganglia, show that the presence of ganglia is not absolutely
necessary in order to have rhythmical pulsation. Direct stimulation
of the heart may cause these movements. But the ganglia are more
excitable than the heart-muscle itself, and they conduct the impulses

100 STANNIUS' EXPERIMENT.

which lead to the regular alternating action of the various parts of the
heart, so that under normal circumstances, we must assume that the
action of the heart is governed by the ganglia.

The chief experiments upon which the above statements are based
consist of two classes: (1.) Where the heart is INCISED or DIVIDED;
and (2.) where it is STIMULATED DIRECTLY.

(I.) Experiments by CUTTING and LIGATURING the heart. These
experiments have been made chiefly upon the frog's heart. The
LIGATURE experiments are performed by tightening and then relaxing
a ligature placed around the heart, so that the physiological connection
is destroyed, while the anatomical or mechanical connections (con-
tinuity of the cardiac wall, intact condition of its cavities) still exist.
The most important of these experiments are

(1.) Stannius' Experiment. If the sinus venosus of a frog's heart
be separated from the auricles, either by an incision or by a ligature,
the auricles and ventricle stand still in diastole, whilst the veins and
the remainder of the sinus continue to beat. If a second incision be
made at the auriculo-ventricular groove, as a rule the ventricle begins
at once to beat again, whilst the auricles remain in the condition of
diastolic rest. According to the position of the second ligature or
incision, the auricles may also beat along with the ventricles, or the
auricles alone may beat, while the ventricles remain at rest (1852).

Explanations. Various explanations of these experiments have been given :
(a.) Remak's ganglion in the sinus vinosus is distinguished by its great excitability,
while Bidder's ganglion in the auriculo-ventricular groove is less excitable ; in the
normal condition of the heart the motor impulse is carried from the former to the
latter. If the sinus venosus be separated from the heart, Remak's ganglion has no
action on the heart. The heart stops for two reasons first, because Bidder's
ganglion alone has not sufficient energy to excite it to action, and because
the inhibitory fibres of the vagus going to the heart have been stimulated by
being divided at this point (Heidenhain). [That stimulation of the inhibitory
fibres of the vagus is not the cause of the standstill, is proved by the fact that the
standstill occurs even after the administration of atropine, which paralyses the
cardiac inhibitory mechanism.] The passive heart, however, may be made to
contract by mechanically stimulating Bidder's ganglion e.g., by a slight prick
with a needle in the auriculo-ventricular groove (H. Munk), or by the action of a
constant current of moderate strength (Eckhard), the ventricular pulsation at the
same time preceding the auricular (v. Bezold, Bernstein). If the auriculo-
ventricular groove be divided, the ventricle pulsates again, because Bidder's ganglion
has been stimulated by the act of dividing it; while, at the same time, the ventricle
is withdrawn from the inhibitory influence of the vagus produced by the first
division at the sinus venosus. If the line of separation is so made that Bidder's
ganglion remains attached to the auricles, these pulsate, and the ventricle rests ;
if it be divided into halves, the auricles and ventricles pulsate, each half being
excited by the portion of the ganglion in relation with it. (b.~) According to
another view, both Remak's (a.) and Bidder's ganglia (b.) are motor centres, but
in the auricles there is in addition an inhibitory ganglionic system (c.) (Bezold,
Traube). Under normal circumstances a + b is stronger than c, while c is stronger

LIGATURE AND SECTION OF THE HEART. 101

than a or b separately. If the sinus venosus be separated it beats in virtue of a;
on the other hand, the heart rests because c is stronger than b. If the section be
made at the level of the auriculo-ventricular, the auricles stand still owing to c,
while the ventricle beats owing to 6.

(2.) If the ventricle of a frog's heart be separated from the rest of
the heart by means of a LIGATURE, or by an INCISION carried through
it at the level of the auriculo-ventricular groove, the sinus and atria
pulsate undisturbed as before (Descartes, 1644), but the ventricle stands
still in diastole. Local stimulation of the ventricle causes a swrjh
contraction. If the incision be so made that the lower margin of the
auricular septum remains attached to the ventricle, the latter pulsates
(Rosenberger, 1850).

(3.) Section of the Heart. Engelmann's recent experiments show
that if the ventricle of a frog's heart be cut up into two or more strips
in a zig-zag way, so that the individual parts still remain connected
with each other by muscular tissue, the strips still beat in a regularly
progressive, rhythmical manner, provided one strip is caused to con-
tract. The rapidity of the transmission is about 10 to 30 mm. per sec.
(Engelmann). Hence, it appears that the conducting paths for the
impulse causing the contraction are not nervous, but must be the
contractile mass itself. It has not been proved that nerve-fibres
proceed from the ganglia to all the muscles.

[According to Marchand's experiments, it takes a very long time for the excite-
ment to pass from the auricles to the ventricle a much longer time, in fact, than
it would require to conduct the excitement through muscle so that it is probable
that the propagation of the impulse from the auricles to the ventricle is conducted
by nervous channels to the auriculo-ventricular nervous apparatus. In fact, in the
mammalian heart the muscular fibres of the auricles are quite distinct from those
of the ventricle.]

(4.) It is usually stated that when the apex of a frog's heart is severed
from the rest of the heart, it no longer pulsates (Heidenhain, Goltz), but
such an apex, if stimulated mechanically, responds with a single con-
traction.

Action of Fluids on the Heart. Haller was of opinion, that
the venous blood was the natural stimulus which caused the
heart to contract. That this is not so, is proved at once by the fact
that the heart beats rhythmically when it contains no blood.

Blood and other fluids which are supplied to an excised heart are
not the cause of its rhythmical movements, but only the conditions on
which these movements depend. Thus, a heart which is too feeble to
contract may be made to do so by supplying it with a fluid containing
proteids, when a latent intra-cardiac mechanism is brought into action,
the albuminous or other fluid merely supplying the pabulum for the
excitable elements.

102

ACTION OF FLUIDS ON THE HEART.

[Methods. The action of fluids upon the excised frog's heart has been rendered
possible by the invention of the "frog-manometer" of Ludwig. The apparatus
has been improved by Ludwig's pupils, and already numerous important results
have been obtained. The apparatus, Fig. 32 consists of (1.) a double-way
cannula, c, which is tied into the heart, li; (2. ) a manometer, m, connected with c,
and registering the movements of its mercury on a revolving cylinder, cyl ; (3.)
two Mariotte's flasks, a and b, which are connected with the other limb of the
cannula. Either a or b can be placed in communication with the interior of the
heart by means of the stop-cock, s. The fluid in one graduated tube may be
poisoned," and the other not; d is a glass vessel for fluid, in which the heart
pulsates, c and <>' are electrodes, e is inserted into the fluid in d, e' is attached to
the german silver cannula which is shown in Fig. 32.

Fig. 32.

Scheme of a frog-manometer a, b,
Mariotte's flasks for the nutrient
fluids ; s, stop-cock ; c, cannula ;
m, manometer ; h, heart ; d, glass
cup for h ; e, c', electrodes ; cyl,
revolving cylinder.

d

Fig. 32a.

Double-way or perfu-
sion cannula (nat.
size) for a frog's
heart c, for fixing
an electrode ; d, the
heart is tied over the
flanges, preventing
it from slipping out ;
e, section of d.

In the tonometer of Roy (Fig. 33) the ventricle, h, or the whole heart, is placed
in an air-tight chamber, o, filled with oil, or with oil and normal saline solution.
As before, a "perfusion" cannula is tied into the heart. A piston, p, works up
and down in a cylinder, and is adjusted by means of a thin flexible animal mem-
brane, such as is used by perfumers. Attached to the piston by means of a thread
is a writing lever, I, which records the variations of pressure within the
chamber, o. When the ventricle contracts, it becomes smaller, diminishes
the pressure within o, and hence the piston and lever rise ; conversely, when
the heart dilates, the lever and piston descend. Variations in the volume of
the ventricle may be registered, without in any way interfering with the flow
of fluids through it.

Two preparations of the frog's heart have been used (1.) The "heart," in which
case the cannula is introduced into the heart through the sinus venosus, and a

ACTION OF FLUIDS ON THE HEART.'

103

ligature is tied over it around the auricle, or it may be the sinus venosus. Thus
the aiiriculo-ventricular ganglia and other nervous structures remain in the pre-
paration. This was the heart preparation employed by Luciani and Rossbach.
(2.) In the " henrt-apex " preparation the cannula is introduced as before, but the
ligature is^tied on it on the ventricle, several millimetres below the auriculo-

Fig. 33.

Roy's apparatus or tonometer for the heart 7t, heart; o, air-tight chamber;

p, piston; I, writing lever.

ventricular groove, so that this preparation contains none of the auriculo- ventricu-
lar ganglia, and, according to the usual statement, this part of the heart is devoid
of nerve ganglia. This is the preparation which was used by Bowditch, Kronecker
and Stirling, Merunowicz, and others. The first effect of the application of the
ligature in both cases is, that both preparations cease to beat, but the "heart"
usually resumes its rhythmical contractions within several minutes, while the
"heart-apex" does not contract spontaneously until after a much longer time
(10to90mins.).

If the " Heart- Apex " be filled with a O'G percent, solution of common salt,
the contractions are at first of greater extent, but they afterwards cease, and
the preparation passes into a condition of "apparent death;" while if the action
of the fluid be prolonged, the heart may not contract at all, even when it is
stimulated electrically or mechanically. It may be made, however, to pulsate
again, if it be supplied with saline solution containing blood (1 to 10 per
cent). The "stille" or state of quiescence may last 90 mins. (Kronecker and
Merunowicz). If the ventricle be nipped with wire forceps at the junction of the
upper with its middle third, so as to separate the lower two-thirds of the ventrical
physiologically but not anatomically from the rest of the heart, then the apex will
cease to contract, although it is still supplied with the frog's own blood (Bernstein,
Bowditch). The physiologically isolated apex may be made to beat by clamping
the aortic branches to prevent blood passing out of the heart, and thus raising the
intracardial pressure. The rate of the beat of the apex is independent of and
slower than that of the rest of the heart. This experiment proves that the
amount of pressure within the apex cavity is an important factor in the
causation of the spontaneous apex beats (Gaskell). If blood-serum, to which
a trace of delphinin is added, be transfused or "perfused" through the heart,
it begins to beat within a minute, continues to beat for several seconds, and
then stands still in diastole (Bowditch). Quinine (Schtschepotjew) and a mixture

104 ACTION OF FLUIDS ON THE HEART.

of atropine and muscarin have a similar action (v. Basch). These experiments
show that, provided no nervous apparatus exists within the heart-apex, the cause of
the varying contraction is to be sought for in the musculature of the heart
(Kronecker), and that the stimulus necessary for the systole of the heart's-
apex may arise within itself (Aubert). If there is no nervous apparatus of any-
kind present, then we must assume that the heart-muscle may execute rhythmical
movements independently of the presence of any nervous mechanism, although it
is usually assumed that the ganglia excite the heart-muscle to pulsate rhythmically.
It is by no means definitely proved that the heart-apex is devoid of all nervous
structures, which may act as originators of these rhythmical impulses.

The "Heart" preparation in many respects behaves like the foregoing, i.e.,
it is exhausted after a time by the continued application of normal saline
solution (0'6 per cent. NaCl), while its activity may be restored by supplying it
with albuminous and other fluids (p. 99).]

[(5.) Luciani found that such a heart, when filled with pure serum,
produced groups of pulsations with a long diastolic pause between every
two groups (Fig. 34). The successive beats in each group assume a
"staircase" character (p. 107). These periodic groups undergo many

Fig. 34.

Four groups of pulsations with intervening pauses, as obtained by Luciani, with
their "staircase" character. The points on the abscissa were marked every
ten seconds.

changes ; they occur when the heart is filled with pure serum free
from blood-corpuscles, and they disappear and give place to regular
pulsations when defibrinated blood or serum containing haemoglobin
or normal saline solution (Kossbach) is used. They also occur when
the blood within the heart has become dark-coloured i.e., when it
has been deprived of certain of its constituents and if a trace of
veratrin be added to bright-red blood they occur.]

(6.) The same apparatus permits of the application of electrical stimuli
to either of the above-named preparations. An apex-preparation, when
stimulated with even a weak induction shock, always gives its maximal
contraction, and when a tetanising current is applied tetanus does not
occur (Kronecker and Stirling). When the opening and closing
shocks of a sufficiently strong constant current are applied to the
heart-apex, it contracts with each closing or opening shock. [When
a constant current is applied to the lower two-thirds of the ventricle
(heart-apex), under certain conditions the apex contracts rhythmically.

ACTION OF HEAT ON THE HEART.

105

This is an important fact in connection with any theory of the cardiac
beat.]

(7.) If the bulbus aorta? (frog) be ligatured, it still pulsates, provided
the internal pressure be moderate. Should it cease to beat, a single
stimulus makes it respond by a series of contractions. Increase of
temperature to 35C., and increase of the pressure within it increase
the number of pulsations (Engelmann).

(II.) Direct Stimulation of the Heart. All direct cardiac stimuli act
more energetically on the inner than on the outer surface of the heart.
If strong stimuli are applied for too long a time, the ventricle is the
part first paralysed.

(a.) Thermal Stimuli. [Heat affects the number or frequency anil the
amplitude of the pulsations, as well as the duration of the systole and diastole and
the excitability of the heart.] Descartes (1614) observed that heat increased the
number of pulsations of an eel's heart. A. v. Humboldt found that when a frog's
heart was placed in lukewarm water, the number of beats increased from 12 to 40
per minute. As the temperature increases, the number of beats is at first con-
siderably increased, but afterwards the beats again become fewer, and if the
temperature is raised above a certain limit the heart stands still, the myosin of
which its fibres consist is coagulated, and "heat-rigor" occurs. Even before
this stage is reached, however, the heart may stand still, the muscular fibres

a

Fig. 35.
Fig. a, Contractions of a frog's heart at 19C.; ba,t 34C.; c, at 3C.

100 ACTION OF MECHANICAL AND ELECTRICAL STIMULI.

appearing to remain contracted. The ventricles usually cease to beat before the
auricles (Schelske). The size and extent of the contractions increase up to about
20C., but above this point they diminish (Fig. 35). The time occupied by any
single contraction at 20C. is only about -^ of the time occupied by a contraction
occurring at 5"C.

A heart which has been warmed is capable of reacting pretty rapidly to inter-
mittent stimuli, while a heart at a low temperature reacts only to stimuli occurring
at a considerable interval. If a frog be kept in a cold place its heart beats slowly
and does little work, but if the heart be supplied with the extract of a frog which
has been kept warm, it is rendered more capable of doing work (Gaule).

Cold. When the temperature of the blood is diminished, the heart beats slower
(Kielmeyer, 1793). A frog's heart, placed between two watch-glasses and laid on
ice, beats very much slower (Ludwig, 1861). The pulsations of a frog's heart stop
when the heart is exposed to a temperature of 4C. to (E. Cyon). If a frog's
heart be taken out of warm water, and suddenly placed upon ice, it beats more
rapidly, and conversely, if it be taken from ice and placed in warm water, it beats
more slowly at first and more rapidly afterwards (Aristow).

[Methods. The effect of heat on a heart may be studied by the aid of the frog-
manometer, the fluid in which the heart is placed being raised to any temperature
required. For demonstration purposes, the heart of a pithed frog is excised and
placed on a glass slide under a light lever, such as a straw. The slide is warmed
by means of a spirit-lamp. In this way the frequency and amplitude of the con-
tractions are readily made visible at a distance.]

[Gaskell fixes the heart by means of a clamp placed round the auriculo-ven-
tricular groove, while levers are placed horizontally above and below the heart.
These levers are fixed to part of the auricles and to the apex by means of threads.
Each part of the heart attached to a lever, as it contracts, pulls upon its own
lever, so that the extent and duration of each contraction may be registered. This
method is applicable for studying the effect of the vagus and other nerves upon the
heart (Roy).]

(&.) Mechanical Stimuli. Pressure applied externally to the heart accelerates
its action. In the case of Frau Serafin, v. Ziemssen found, that slight pressure on
the auriculo- ventricular groove caused a second short contraction of both ventricles
after the heart-beat. Strong pressure causes a very irregular action of the cardiac
muscle. This may readily be produced by compressing the freshly excised heart
of a dog between the fingers.

The intra-cardiac pressure also affects the heart-beat. If the pressure within the
heart be increased, the heart-beats are gradually increased, if it be diminished the
number of beats diminishes (Ludwig and Thiry). If the intra-cardiac pressure be
very greatly increased, the heart's action becomes very irregular aud slower
(Heidenhain). A heart which has ceased to beat may, under certain circum-
stances, be caused to execute a single contraction if it be stimulated mechanically.

(c.) Electrical Stimuli. A constant electrical current of moderate strength
increases the number of heart-beats, v. Ziemssen found in the case of Frail
Serafin (p. 74, 3), that the number of beats was doubled, when a constant uninter-
rupted strong current was passed through the ventricles. If the constant current
be very strong, or if tetanising induction currents be used, the cardiac muscle
assumes a condition resembling, but not identical with, tetanus (Ludwig and
Hoffa), and of course this results in a fall of the blood- pressure (Sigm. Mayer).

When a single induction shock is applied to the ventricle of a frog's heart during
systole, it has no apparent effect ; but if it is applied during diastole, the succeeding
contraction takes place sooner. The auricles behave in a similar manner. Whilst
they are contracted, an induction shock has no effect ; if, however, the stimulus is
applied during diastole, it causes a contraction, which is followed by systole of the

ACTION OF ELECTRICAL STIMULI ON THE HEART. 107

ventricle (Hildebrand). Even when strong tetanising induction-shocks are applied
to the heart, they do not produce tetanus of the entire cardiac musculature, or as it
is said, "the heart knows no tetanus" (Kronecker and Stirling). Small white local
weal-like elevations such as occur when the intestinal musculature is stimulated
appear between the electrodes. They may last several minutes. A frog's heart,
which yields weak and irregular contractions, may be made to execute regular
rhythmical contractions isochronous with the stimuli, if electrical stimuli are used
(Bowditch). In this case the weakest stimuli (which are still active) behave like
the stronger stimuli even with the weak stimulus the heart always gives the
strongest contraction possible. Hence this minimal electrical stimulus is as
effective as a "maximal" stimulus (Kronecker and Stirling).

V. Ziemssen found that he could not alter the heart-beats of the Imman heart (Frau
Serafin, p.74,3), even with strong induction currents. The ventricular diastole seemed
to be less complete, and there were irregularities in its contraction. By opening and
closing, or by reversing a strong constant current applied to the heart, the number
of beats was increased, and the increase corresponded with the number of electrical
stimuli; thus, when the electrical stimuli were 120, 140, 180, the number of heart-
beats was the same, the pulse beforehand being SO. When ISO shocks per minute
were applied the action of the heart assumed the characters of the pulsus alternans
(p. 143). Minimal stimuli were also found to act like maximal stimuli. The
normal pulse-rate of SO was reduced to 60 and 50, when the number of shocks was
reduced in the same ratio. The rhythm became at the same time somewhat
irregular. In these experiments a strong current is required, and v. Basch found
that the same was true for the frog's heart. Even in healthy persons, v. Ziemssen
ascertained that the energy and rhythm of the heart could be modified by passing
an electrical current through the uninjured chest-wall.

[Method. The apparatus (Fig. 32.) is also well adapted for studying the effect
of electrical currents upon the heart. Bowditch, Kronecker and Stirling, and
other observers, used the " heart-apex," as it does not contract spontaneously
for some time after the ligature is applied. One electrode is attached to the
canuula, and the other is placed in the fluid in which the heart is bathed.]

[Opening induction shocks, if of sufficient strength, cause the heart to con-
tract, while weak stimuli have no effect; on the other hand, moderate stimuli,
when they do cause the heart to contract, always cause a maximal contrac-
tion, so that a minimal stimulus acts at the same time like a maximal stimulus.
The heart either contracts or it does not contract, and when it contracts the
result is always a "maximal" contraction. Bowditch found, that the excit-
ability of the heart was increased by its own movements, so that after a heart
had once contracted, the strength of the stimulus required to excite the next
contraction may be greatly diminished, and yet the stimulus be effectual. Usually
the amplitude of the first beat so produced is not so great as the second beat, and
the second is less than the third, so that a " staircase " (" Treppe ") of beats
of successively greater extent are produced (Fig. 34. ) This staircase arrangement
occurs even when the strength of the stimulus is kept constant, so that the produc-
tion of one contraction facilitates the occurrence of the succeeding one. A staircase
arrangement of the pulsations is also seen in Luciani's groups (p. 104). The ques-
tion, whether a stimulus will cause a contraction, depends upon what
particular phase the heart is iu, when the shock is applied. Even comparatively
weak stimuli will cause a heart to contract, provided the stimuli are applied at
the proper moment and in the proper tempo i.e. to say, they become what
are called "infallible." If stimuli are applied to the heart, at intervals which
are longer than the time the heart takes to execute its contraction, they are
effectual or "adequate," but if they are applied before the period of pulsation
comes to an end, then they are ineffectual (Kronecker). It is quite clear, there-

108 ACTION OF CHEMICAL STIMULI AND GASES ON THE HEART.

fore, that the relation of the strength of the stimulus, to the extent of the contrac-
tion of the cardiac muscle, is quite different from what occurs in a muscle of the
skeleton, where within certain limits the amplitude of the contraction bears a
relation to the stimulus, while in the heart the contraction is always maximal.]

(rf.) Chemical Stimuli. Many chemical substances, when applied in a dilute
solution, to the inner surface of the heart, increase the heart-beats, while if
they are concentrated or allowed to act too long, they diminish the heart-beats,
and paralyse it. Bile (Budge), bile salts (Rohrig) diminish the heai't-beats (also
when they are absorbed into the blood as in jaundice) ; in very dilute solutions
both increase the heart-beats (Landois). A similar result is produced by acetic,
tartaric, citric (Bobrik), and phosphoric acids (Leyden). Chloroform and ether,
applied to the inner surface, rapidly diminish the heart-beats, and then paralyse it;
but very small quantities of ether (1 per cent.) accelerate the heart-beat of the frog
(Kronecker and M'Gregor-Robertson), while a solution of 1| to 2 per cent, passed
through the heart arrests it temporarily or completely. A dilute solution of
opium, strychnia, or alcohol applied to the endocardium, increases the heart-beats
(C. Ludwig) ; if concentrated they rapidly arrest its action. Chloral-hydrate
paralyses the heart (P. v. Rokitansky).

Action of Gases. When blood containing different gases was passed through
a frog's heart, Klug found that blood containing sulphurous acid rapidly and
completely killed the heart ; chlorine stimulated the heart at first, and ultimately
killed it ; and laughing-gas rapidly killed it also. Blood containing sulphuretted
hydrogen paralysed the heart without stimulating it. Carbonic oxide also
paralysed it, but if fresh blood was transfused, the heart recovered. [Blood con-
taining excites the heart (Castell), while the presence of much COo paralyses it,
and the presence of COo is more injurious than the want of 0. H and N have no
effect.]

Rossbach found on stimulating the ventricle of a frog's heart at a circumscribed
area, either mechanically, chemically, or electrically, during systole, that the
part so stimulated relaxes in partial diastole. The immediate direct after-effect
of this stimulation is. that the muscular fibres in the part irritated remain some-
what shrivelled. This part ceases to act, and has lost its vital functions. If the
stimulus is applied during diastole, the part irritated always relaxes sooner, and
its diastole lasts longer than does that of the parts which were not stimulated.
If weak stimuli are allowed to act for a long time upon any part of the ventricle
of a frog's heart, the part so stimulated always relaxes sooner than the non-stimu-
lated parts, and its diastole is also prolonged.

Cardiac Poisons are those substances whose action is characterised by special
effects upon the movements of the heart. Amongst these are the neutral salts of
potash. [Until 1863 it was believed that these salts were just as slightly active on
the heart as the soda salts, but Bernard and Grandeau showed that very small
doses of these salts produced death, the heart standing still in diastole. An
excised frog's heart ceases to beat after one-half to one minute when it is placed in
a 2 per cent, solution of potassic chloride.] Even a very dilute solution of yellow
prussiate of potash injected into the heart of a frog causes the ventricle to stand
still in systole.

As early as 1691, Clayton and Moulin showed the poisonous action of potassium
sulphate, and alum, as compared with the non-poisonous action of sodium chloride,
which was demonstrated by Courten in 1679. Anliar (Java arrow-poison) causes
the ventricle to stand still in systole and the auricles in diastole. Some heart-
poisons in small doses, diminish the heart's action, and in large doses not unfre-
quently accelerate it e.g., digitalis, morphia, nicotin. Others, when given in
small doses, accelerate ita action, and in large doses slow it veratria, aconitin,
camphor.

NATURE OF A CARDIAC CONTRACTION. 109

Special Actions Of Cardiac Poisons. The complicated actions of various
poisons upon the heart, have led observers to suppose that there are various intra-
cardiac mechanisms on which these substances may act. Besides the muscular
fibres of the heart and its automatic ganglia, some toxicologists assume that there
are inhibitory ganglia into which the inhibitory fibres of the vagus pass, and
accelerator ganglia, which are connected with the accelerating nerve-fibres of the
heart. Both the inhibitory and accelerator ganglia are connected with the automatic
ganglia by conducting channels.

Muscarin stimulates permanently the inhibitory ganglia, so that the heart
stands still (Schmiedeberg and Koppe). As atropin and daturin paralyse these
ganglia, the stand-still of the heart brought about by muscarin may be set aside by
atropin. [If a frog's heart be excised and placed in a watch-glass, and a few drops
of a very dilute solution of muscarin be placed on it with a pipette, it ceases to
beat within a few minutes, and will not beat again. If, however, the muscarin be
removed, and a solution of atropine applied to the heart, it will resume its contrac-
tions after a short time.] Physostigmin [Calabar bean] excites the energy of the
cardiac muscle to such an extent, that stimulation of the vagus no longer causes
the heart to stand still. lodine-aldehyd, chloroform, and chloral-hydrate paralyse
the automatic ganglia. The heart stands still, and it cannot be made to contract
again by atropine. The cardiac muscle itself remains excitable after the action of
muscarin and iodine -aldehyd, so that if it be stimulated it contracts. [According
to Gaskell, antiarin aud digitalin solutions produce an alteration in the condition
of the muscular tissue of the apex of the heart of the same nature as that pro-
duced by the action of very dilute alkali solution, while the action of a blood solution
containing muscarin closely resembles that of a dilute acid solution ( 65).]

[Nature of a Cardiac Contraction. The question as to whether
this is a simple contraction or a compound tetanic contraction, has been
much discussed. This much is certain, that the systolic contraction
of the heart is of very much longer duration (8 to 10 times) than the
contraction of a skeletal muscle produced by stimulation of its motor
nerve. When the sciatic nerve of a nerve-muscle preparation (" rheo-
scopic limb") is adjusted upon a contracting heart, a simple secondary
twitch of the limb, and not a tetanic spasm, is produced when the
heart (auricle or ventricle) contracts. This of itself is not sufficient
proof that the systole is a simple spasm, for tetanus of a muscle does
not in all cases give rise to secondary tetanus in the leg of a rheoscopic
limb. Thus, a simple " initial " contraction occurs, when the nerve is
applied to a muscle tetanised by the action of strychnia, and the con-
tracted diaphragm gives a similar result. The question as to whether
the heart can be tetanised, has been answered in the negative, and as
yet it has not been shown that the heart can be tetanised in the same
way that a skeletal muscle is tetanised.]

The peripheral or extra-cardiac nerves will be discussed in connec-
tion with the Nervous System.

59, The Cardio-Pneumatic Movement,

As the heart within the thorax occupies a smaller space during the
systole than during the diastole, it follows that when the glottis is open,

110

THE CARDIO-PNEUMATIC MOVEMENT.

air must be drawn into the chest when the heart contracts ; whenever
the heart relaxes, i.e., during diastole, air must be expelled through the
open glottis. But we must also take into account the degree to which
the larger intrathoracic vessels are filled with blood. These movements
of the air within the lungs, although slight, seem to be of importance
in hybernating animals. In animals in this condition, the agitation of
the gases in the lungs favours the exchange of C0 2 and in the lungs,
and this slow current of air is sufficient to aerate the blood passing
through the lungs. [Ceradini called the diminution of the volume of
the entire heart which occurs during systole meiocardie, and the
subsequent increase of volume when the heart is distended to its
maximum, auxocardie.]

Method. The cai'do-pneumatic movements i.e., the movement of the respira-
tory gases dependent on the movements of the heart and great vessels may be
demonstrated in animals and man. A manometric flame may be used. Insert one
limb of a Y-tube into the opened trachea of an animal, while the other limb passes
to a small gas-jet, and connect the other tube with a gas-jet. It is clear that the
movements of the heart will affect the column of gas, and thus affect the flame.
Large animals previously curarised are best. It may also be done in man by
inserting the tube into one nostril, while the other nostril and the mouth are
closed. [A simpler and less irritating plan is to till a wide curved glass-tube with
tobacco smoke, and insert one end of the tube into one nostril while the other nostril
and the mouth are closed. If the glottis be kept open, and respiration be stopped,
then the movements of the column of smoke within the tube are obvious.]

Fig. 36.

Landois' cardio-pueumograph, and the curves obtained therewith A and B, from
man, 1 and 2, correspond to the periods of the first and second heart-sounds;
C, from dog; D, method of using the apparatus.

Cardio-Pneumograph. Ceradini employed a special instrument, while
Landoia uses his cardio-pneumograph which consists of a tube (D), about one inch

INFLUENCE OF RESPIRATORY PRESSURE ON THE HEART. Ill

in diameter and six to eight inches iu length; the tube is bent at a right angle,
and communicates with a small metal capsule about the size of a saucer (T), over
which a membrane composed of collodion and castor oil is loosely stretched. To
this membrane is attached a glass-rod (H) used as a writing-style, which records
its movements on a glass-plate (S) moved by clock-work. A small valve (K) is
placed on the side of the tube (D), which enables the experimenter to breathe
when necessary. The tube (D) is held in an air-tight manner between the lips,
the nostrils being closed, the glottis open, and respiration stopped. Fig. 36,
A, B, C, are curves obtained in this way. In them we observe

(a) At the moment of the first sound (1.), the respiratory gases undergo a sharp
expiratory movement, because at the moment of the first part of the ventricular
systole the blood of the ventricle has not left the thorax, while venous blood is
streaming into the right auricle through the venaa cav*, and because the dilating
branches of the pulmonary artery compress the accompanying bronchi. The
blood of the right ventricle has not yet left the thorax, it passes merely into
the pulmonary circuit. The expiratory movement is diminished somewhat by (a)
the muscular mass of the ventricle occupying slightly less bulk during the contrac-
tion, and (/3) owing to the thoracic cavity being slightly increased by the fifth
intercostal space being pushed forward by the cardiac impulse.

(b) Immediately after (1. ), there follows a strong inspiratory current of the respira-
tory gases. As soon as the blood from the root of the aorta reaches that part of
the aorta lying outside the thorax, more blood leaves the chest than passes into it
simultaneously through the vente cavae.

(c) After the second sound (at 2.), indicated sometimes by a slight depression in
the apex of the curve, the arterial blood accumulates, and hence there is another
expiratory movement in the curve.

(d) The peripheral wave-movements of the blood from the thorax cause another
inspiratory movement of the gases.

(e) More blood flows into the chest through the veins, and the next heart-beat
occurs.

60. Influence of the Respiratory Pressure on the
Dilatation and Contraction of the Heart.

The variation ia pressure to which all the intra-thoracic organs are
subjected, owing to the increase and decrease in the size of the chest
caused by the respiratory movements, exerts an influence on the move-
ments of the heart, as was proved by Carson in 1820, and by Donders
in 185 4. Examine first the relations in different passive conditions of
the thorax, when the glottis is open.

The diastolic dilatation of the cavities of the heart (excluding the
pressure of the venous blood and the elastic stretching of the relaxed
muscle-wall) is fundamentally due to the elastic traction of the lungs.
This is stronger the more the lungs are distended (inspiration), and is
less active the more the lungs are contracted (expiration). Hence it
follows :

(1.) When the greatest possible expiratory effort is made (of course,
with the glottis open) only a small amount of blood flows into the
cavities of the heart ; the heart in diastole is small and contains a small

112 VALSALVA AND MULLEIl's EXPERIMENTS.

amount of blood. Hence the systole must also be small, which further
gives rise to a small pulse-beat.

(2.) On taking the greatest possible inspiration, and therefore causing
the greatest stretching of the elastic tissue of the lungs, the elastic
traction of the lungs is, of course, greatest 30 mm. Hg. (Bonders).
This force may act so energetically as to interfere with the contraction
of the thin-walled atria and appendices, in consequence of which these
cavities do not completely empty themselves into the ventricles. The
heart is in a state of great distension in diastole, and is filled with
blood ; nevertheless, in consequence of the limited action of the auricles,
only small pulse-beats are observed. In several individuals Bonders
found the pulse to be smaller and slower; afterwards it became larger
and faster.

(3.) When the chest is in a position of moderate rest, whereby the
elastic traction is moderate (7*5 mm. Hg. Bonders), we have the condi-
tion most favourable to the action of the heart sufficient diastolic
dilatation of the cavities of the heart, as well as unhindered emptying
of them during systole.

A very important factor, is the influence exerted upon the action of
the heart, by the voluntary increase or diminution of the intra-thoracic
'pressure.

(1.) Valsalva's Experiment. If the thorax is fixed in the position
of deepest inspiration, and the glottis be then closed, and if a powerful
expiratory effort be made by bringing into action all the expiratory
muscles, so as to contract the chest, the cavities of the heart are so
compressed that the circulation of the blood is temporarily interrupted.
In this expiratory phase the elastic traction is very limited, and the air
in the lungs being under a high pressure also acts upon the heart and
the intra-thoracic great vessels. No blood can pass into the thorax
from without ; hence the visible veins swell up and become congested,
the blood in the lungs is rapidly forced into the left ventricle by the
compressed air in the lungs, and the blood soon passes out of the chest.
Hence the lungs and the heart contain little blood. Hence also there
is a greater supply of blood in the systemic than in the pulmonary
circulation and the heart. The heart-sounds disappear, and the pulse
is absent (E. H. Weber, Bonders).

(2.) J. Miiller's Experiment. Conversely, if after the deepest pos-
sible expiration the glottis be closed, and the chest be now dilated with
a great inspiratory effort, the heart is powerfully dilated, the elastic
traction of the lungs, and the very attenuated air in these organs act
so as to dilate the cavities of the heart in the direction of the lungs.
More blood flows into the right heart, and in proportion as the right
auricle and ventricle can overcome the traction outwards, the blood-

INFLUENCE OF THE RESPIRATION ON THE HEART.

113

vessels of the lungs become filled with blood, and thus partly occupy
the lung-space. Much less blood is driven out of the left heart, so that
the pulse may disappear. Hence, the heart is distended with blood,
and the lungs are congested, while the aortic system contains a small
amount of blood i.e., the systemic circulation is comparatively empty,
while the heart and the pulmonary vessels are engorged with blood.

In normal respiration, the air in the lungs during inspiration is
under slight pressure, while during expiration the pressure is higher,
so that these conditions favour the circulation ; inspiration favours the
supply of blood (and lymph) through the vena? cavae, and favours the
occurrence of diastole. In operations where the axillary or jugular
vein is cut, air may be sucked into the circulation during inspiration,
and cause death. Expiration favours the flow of blood in the aorta
and its branches, and aids the systolic emptying of the heart. The
arrangement of the valves of the heart causes the blood to move in a
definite direction through it.

a

II

Fte .37.

Apparatus for demonstrating the action of inspiration, II, and expiration, I, on
the heart and on the blood-stream P, p, lungs ; H, h, heart ; L, /, closed
glottis ; M, m, manometers ; E, e, ingoing blood-stream, vein ; A, a, outgoing
blood-stream, artery ; D, diaphragm during expiration ; d, during inspiration.

8

114 INFLUENCE OF THE RESPIRATION ON THE HEART.

The elastic traction of the lungs aids the lesser circulation through the
lungs within the chest; the blood of the pulmonary capillaries is
exposed to the pressure of the air in the lungs, while the blood in the
pulmonary veins is exposed to a less pressure, as the elastic traction of
the lungs, by dilating the left auricle favours the outflow from the
capillaries into the left auricle. The elastic traction of the lungs acts
slightly as a disturbing agent on the right ventricle, and, therefore,
on the movement of blood through the pulmonary artery, owing to
the overpowering force of the blood-stream through the pulmonary
artery, as against the elastic traction of the lungs (Bonders).

The above apparatus (Fig. 37) shows the effect of the inspiratory and expiratory
movements on the dilatation of the heart, and on the blood-stream in the large
blood-vessels. The large glass- vessel represents the thorax; the elastic mem-
brane, D, the diaphragm ; P, j>, the lungs ; L, the trachea supplied with a stop-coclc
to represent the glottis ; H, the heart ; E, the venas cavaj ; A, the aorta. If the
glottis be dosed, and the expiratory phase imitated by pushing up D as in I, the
air in P, P is compressed, the heart, H, is compressed, the venous valve closes,
the arterial is opened, and the fluid is driven out through A. The manometer,
M, indicates the intrathoracic pressure. If the glottis be closed, and the
inspiratory phase imitated, as in II, p, p and li are dilated, the venous valve
opens, the arterial valve closes ; hence, venous blood flows from e into the heart.
Thus, inspiration always favours the venous stream, and hinders the arterial ;
while expiration hinders the venous, and favours the arterial stream. If the
glottis L and /, be open, the air in P, P, p, p will be changed during the respiratory
movements D and d, so that the action on the heart and blood-vessels will be
diminished, but it will still persist, although to a much less extent.

The Circulation,

61. The Flow of Fluids through Tubes.

Toricelli's Theorem (1643) states that the velocity of efflux (c) of a fluid
through an opening at the bottom of a cylindrical
vessel is exactly the same as the velocity which a body
falling freely would acquire, were it to fall from the
surface of the fluid to the base of the orifice of the out-
flow. If h be the height of the propelling force, the
velocity of efflux is given by the formula

v = V 2 \ g h (where ;/ =; 9 '8 metre).

The rapidity of outflow increases (as shown experi-
mentally) with increase in the height of the propelling
force, Ji. The former occurs in the ratio, 1, 2, 3, when 7t
increases in the ratio, 1, 4, 9 i. e., the velocity of efflux
is as the square root of the height of the propelling
force. Hence, it follows that the velocity of efflux
depends upon the height of the liquid above the orifice
of outflow, and not upon the nature of the fluid.

Resistance. Toricelli's theorem, however, is only
valid when all resistance to the outflow is absent ; but,
in fact, in every physical experiment such resistance
exists. Hence, the propelling force, h, has not only to
cause the ffflux of the fluid, but has also to overcome
resistance. These two forces may be expressed by the
heights of two columns of water placed over each other
viz. , by the height of the column of water causing the
outflow, F, and the height of the column, D, which
overcomes the resistance opposed to the oiitflow of the fluid. So that

h = F + D.

Fig. 38.

Cylindrical vessel filled
with water h, height
of the column of fluid ;
D, height of column of
fluid requii-ed to over-
come the resistance ;
and F, height of
column of fluid caus-
ing the efflux.

62. Propelling Force Velocity of the Current,
and Lateral Pressure.

In the case of a fluid flowing through a tube, which it fills completely, we have
to consider the propelling force, /, causing the fluid to flow through the various
sections of the tube. The amount of the propelling force depends upon two
factors :

(1.) On the velocity of the current, v;

(2.) On the pressure (amount of resistance') to which the fluid is subjected at the
various parts of the tube, D.

(1.) The velocity of the current, v, is estimated (a.) from the lumen, /, of the

116

FLOW OF FLUIDS THROUGH TUBES.

tube ; and (b.) from the quantity of fluid, q, which flows through the tube in
the unit of time. So that v = q : I. Both values, q as well as /, can be accurately
measured. (The circumference of a round tube, whose diameter = d is 3'14.rf.

3 - 14

The sectional area (lumen of the tube) is l=~- . d".) Having in this way

determined v, from it we may calculate the height of the column of fluid, F, which
will give this velocity i.e., the height from which a body must fall in vacuo,

V

in order to attain tlie velocity, r, In this case F - j (where y = the distance

if

traversed by a falling body in 1 sec. = 4'9 metre).

A cylindrical vessel rilled with water a, I, outflow tube, along which are
placed at intervals vertical tubes, 1, 2, 3, to estimate the pressure.

(2.) The pressure, D (amount of resistance), is measured directly by placing
manometers at different parts of the tube (Fig. 39).
ropelling force at any part of the tube is

or,

(Bonders).

This is proved experimentally by taking a tall cylindrical vessel, A, of sufficient
size, which is kept filled with water at a constant level, h. The outflow
rigid tube, a, b, has in connection with it a number of tubes placed vertically
1, 2, 3, constituting a piezometer. At the end of the tube, b, there is an opening
with a short tube fixed in it, from which the water issues to a constant height,
provided the level of h is kept constant. The height to which it rises depends on
the height of the column of fluid causing the velocity, F. As the pressure in the
manometric tubes, B 1 , B 2 , B 3 , can be read off directly, the propelling force of the
water at the sections of the tubes, I, II, III, is

h = + B 1 ;-F + B'-;-F + B 3 .

At the end of the tube, b, where B 4 = 0, A = F + 0, i.e., /* = F. In the cylinder
itself it is the constant pressure, h, which causes the movement of the fluid.

It is clear, that the propelling force of the water gradually diminishes as we pass
from the part where the fluid passes out of the cylinder into the tube towards the
end of the tube, b. The water in the pressure-cylinder, falling from the height, ft,
only rises as high as F at b. This diminution of the propelling power is due to the

ESTIMATION OF RESISTANCE. 117

presence of RESISTANCES, which oppose the current in the tube, i.e., part of the
energy is transformed into heat. As the propelling power at b is represented only
by F, while in the vessel it is h, the difference must be due to the sum of the
resistances, D ~ h - F ; hence it follows that h F -f D (Donders).

Estimation of Resistance.

Estimation Of the Resistance. When a Huid flows through a tube of
uniform calibre the propelling force, k, diminishes from point to point on account
of the uniformly acting resistance, hence the sum of the resistances in the whole
tube is directly proportional to its length. In a uniformly wide tube, fluid flows
through each sectional area with equal velocity, hence v and also F are equal in
all parts of the tube. The diminution which h ("propelling force) undergoes can
only occur from a diminution of pressure D, as F remains the same throughout
(and h = F + D). Experiment with the pressure-cylinder shows, that as a matter
of fact, the pressure towards the outflow end of the tube becomes gradually
diminished.

In a uniformly wide tube, the height of the pressure in the manometers expresses the
resistances opposed to the current of fluid, which it has to overcome in its course
from the point investigated to the free orifice, of efflux.

Nature Of the Resistance. The resistance opposed to the flow of a fluid,
depends upon the cohesion of the particles of the fluid amongst themselves. During
the current, the outer layer of fluid which is next the wall of the tube, and which
moistens it, is at rest (Girard, Poiseuille). All the other layers of fluid, which
may be represented as so many cylindrical layers, one inside the other, move more
rapidly as we proceed towards the axis of the tube, the axial thread or stream
being the most rapidly moving part of the liquid. On account of the movement of
the cylindrical layers, one within the other, a part of the propelling energy must
be used up. The amount of the resistance greatly depends upon the amount of the
cohesive force which the particles of the fluid have for each other ; the more firmly
the particles cohere with each other, the greater will be the resistance, and vice
versa. Hence, the sticky blood-current experiences greater resistance than water
or ether.

Heat diminishes the cohesion of the particles, hence it also diminishes the resistance
to the flow of a current. These resistances are first developed by, and result from,
the movement of the particles of the fluid, they being, as it were, torn from each
other. The more rapid the current, therefore, i.e., the larger the number of
particles of fluid which are pulled asunder in the unit of time, the greater will he
the sum of the resistance. As already mentioned, the layer of fluid lying next the
tube, and moistening it, is at rest, hence the material which composes the tube
exerts no influence on the resistance.

Effect of Tubes of Unequal Calibre,

Unequal Diameter. When the velocity of the current is uniform, the resis-
tance depends upon the diameter of the tube the smaller the diameter, the greater
the resistance ; the greater the diameter, the less the resistance. The resistance in
narrow tubes, however, increases more rapidly than the diameter of the tube
decreases, as has been proved experimentally.

In tubes of unequal calibre, at different parts of their course, the velocity of the
current varies it is slower in the wide part of the tube and more rapid in the

118 CURRENTS THROUGH CAPILLARY TUBES.

narrow parts. As a general rule, in tubes of unequal diameter the velocity of
the current is inversely proportional to the diameter of the corresponding section
of the tube; i.e., if the tube be cylindrical, it is inversely proportional to the square
of the diameter of the circular transverse section. In tubes of uniform diameter, the
propelling force of the moving fluid diminishes uniformly from point to point, but
in tubes of unequal calibre it does not diminish uniformly. As the resistance is
greater in narrow tubes, of course the propelling force must diminish more rapidly
in them than in wide tubes. Hence, withiu the wide parts of the tube the pressure
is greater than the sum of the resistances still to be overcome, while in the narrow
portions it is less than these.

Tortuosities and Bending Of the Vessels add new resistance, and the fluid
presses more strongly on the convex side than on the concave side of the bend,
and there the resistance to the flow is greater than on the concave side.

Division of a tube into two or more branches is a source of resistance, and
diminishes the propelling power. When a tube divides into two smaller tubes, of
course some of the particles of the fluid are retarded, while others are accelerated
on account of the unequal velocities of the different layers of the fluid. Many
particles which had the greatest velocity in the axial layer come to lie more towards
the side of the tube where they move more slowly ; and conversely many of those
lying in the outer layers reach the centre, where they move more rapidly. Hence,
some of the propelling force is used up in this process, and the pulling asunder of
the particles where the tube divides acts in a similar manner. If two tubes join
to form one tube, new resistance is thereby caused which must diminish the
propelling force. The sum of the mean velocities in both branches is independent
of the angle at which the division takes place (Jacobson). If a branch be opened
from a tube, the principal current is accelerated to a considerable extent, no
matter at what angle the branch may be given off.

63. Currents through Capillary Tubes.

Poiseuille proved experimentally, that the flow in the capillaries is subject to
special conditions

(1.) The quantity of fluid which flows out of the same capillary tube is pro-
portional to the pressure.

(2. ) The time necessary for a given quantity of fluid to flow out (with the like
pressure, diameter of tube and temperature), is proportional to the length of
the tubes.

(3.) The product of the outflow (other things being equal) is as the fourth power
of the diameter.

(4.) The velocity of the current is proportional to the pressure and to the square
of the diameter, and inversely proportional to the length of the tube.

(5.) The resistance in the capillaries is proportional to the velocity of the current.

64. Movement of Fluids and Wave-Motion in

Elastic Tubes.

(1.) When an uninterrupted uniform current flows through an elastic tube, it
follows exactly the same laws as if the tube had rigid walls. If the propelling
power increases or diminishes, the elastic tubes become wider or narrower, and
they behave, as far as the movement of the fluid is concerned, as wider or narrower
rigid tubes.

MOVEMENT OF FLUIDS IN ELASTIC TUBES. 119

(2.) Wave-Motion. If however, more fluid be forced in jerks into an elastic
tube, i.e., interruptedly the first part of the tube dilates suddenly, corresponding
to the quantity of fluid propelled into it. The jerk communicates an oscillatory
movement to the particles of the fluid, which is communicated to all the fluid
particles from the beginning to the end of the tube ; a positive wave is thus rapidly
propagated throughout the whole length of the tube. If we imagine the elastic tube
to be closed at its peripheral end, the positive wave will be reflected from the
point of occlusion, and it may be propagated to and fro through the tube until
it finally disappears. In such a closed tube a sudden jet of fluid produces only a
wave-movement, i.e., only a vibratory movement, or an alteration in the shape
of the liquid, there being no actual translation of the particles along the tube.

(3.) If, however, fluid be pumped interruptedly or by jerks into an elastic tube
filled with fluid, in which there is already a continuous current, the movement
of the current is combined with the wave-movement. We must carefully dis-
tinguish the movement of the current of the fluid, i.e., the translation of a mass of
fluid through the tube, from the wave-movement, the oscillatory movement, or
movement of change of form in the column of fluid. In the former, the
particles are actually translated, while in the latter they merely vibrate. The
current in elastic tubes is slower than the wave-movement, which is propagated
with great rapidity.

This last case obtains in the arterial system. The blood in the arteries is
already in a state of continual movement, directed from the aorta to the capillaries
(movement of the current of blood) ; by means of the systole of the left ventricle
a quantity of fluid is suddenly pumped into the aorta, and causes a positive wave
(pulse-wave) which is propagated with great rapidity to the terminations of the
arteries, while the current of the blood itself moves much more slowly.

Rigid and Elastic Tubes. It is of importance to contrast the movement
of fluids in rigid and in elastic tubes. If a certain quantity of fluid be forced
into a rigid tube under a certain pressure, the same quantity of fluid will flow
out at once at the other end of the tube, provided there be no special re-
sistance. In an elastic, tube, immediately after the forcing in of a certain
quantity of fluid, at first only a small quantity flows out, and the remainder
flows out only after the propelling force has ceased to act.

If an equal quantity of fluid be periodically injected into a rigid tube, with
each jerk an equal quantity is forced out at the other end of the tube, and the
outflow lasts exactly as long as the jerk or the contraction, and the pause between
two periods of outflow is exactly the same as between the two jerks or contractions.
In an elastic tube it is different, as the outflow continues for a time after the
jerk; hence, it follows that a continuous outflow current will be produced in
elastic tubes, when the time between two jerks is made shorter than the duration
of the outflow after the jerk has been completed. When fluid is pumped
periodically into rigid tubes, it causes a sharp abrupt outflow isochronous with
the inflow, and the outflow becomes continuous only when the inflow is
continuous and uninterrupted. In elastic tubes, an intermittent current under
the above conditions causes a continuous outflow which is increased with the
systole or contraction.

65. Structure and Properties of the Blood- Vessels.

In the body the large vessels carry the blood to and from the various
tissues and organs, while the thin-walled capillaries bring the blood into

120

STRUCTURE OF ARTERIES.

intimate relation with the tissues. Through the excessively thin walls
of the capillaries the fluid part of the blood transudes, to nourish the
tissues outside the capillaries. [At the same time fluids pass from the
tissues into the blood. Thus, there is an exchange between the blood
and the fluids of the tissues. The fluid after it passes into the tissues
constitutes the lymph, and acts like a stream irrigating the tissue
elements.]

I. The Arteries are distinguished from veins by their thicker
walls, due to the greater development of smooth muscular and
elastic tissues the middle coat (tunica media) of the arteries is
specially thick, while the outer coat (t. adventitia) is relatively thin.

[The absence of valves is by no
means a characteristic feature.]

The arteries consist of three coats
(Fig. 40). (1.) The Tunica intima,
or inner coat, consists of a layer of
(a) irregular, long, fusiform nucleated
squamous cells forming the exces-
sively thin transparent endothelium
(His, 1866), immediately in contact
with the blood-stream. [Like other
endothelial cells, these cells are held
together by a cement substance which
is blackened by the action of silver
nitrate.]

Outside this lies a very thin, more
or less fibrous, layer - - sub-epithelial
hit/cr in which numerous spindle or
branched protoplasmic cells lie em-
bedded within a corresponding system
of plasma canals. Outside this is an
elastic lamina (b\ which in the smallest
jg a structureless O r fibrous

d

Fig. 40.

Small artery to show the various

layers which compose its walls . .

, endothelium; b, internal elastic elasticmembranc in artenesof medium

lamina; c, circular muscular fibres see it isafcnestrated membrane (Henle),

of the middle coat ;</, the connective w hile in the largest arteries there may

tissue outer coat (T. adventitia). , , , i , i

be several layers 01 elastic laminae or

fenestrated elastic membrane mixed with connective tissue. [In some
arteries the elastic membrane is distinctly fibrous, the fibres being
chiefly arranged longitudinally. It may be stripped off', when it forms
a brittle elastic membrane, which has a great tendency to curl up at
its margins. In a transverse section of a middle-sized artery it
appears as a bright wavy line, but the curves are probably produced

STRUCTURE OF ARTERIES. 121

by the partial collapse of the vessel. It forms an important guide to
the pathologist in enabling him to determine which coat of the
artery is diseased.]

In middle-sized and large arteries a few non-striped muscular fibres
are disposed kncjitudinally between two elastic plates or lamina? (K.
Bardeleben). Along with the circular muscular fibres of the middle
coat, they may act so as to narrow the artery, and they may also aid in
keeping the lumen of the vessel open and of uniform calibre. It
is not probable that when they act by themselves they dilate the
vessel.

(2.) The Tunica media, or middle coat, contains much non-striped
muscle (c), which in the smallest arteries consist of transversely disposed
non-striped muscular fibres lying between the endothelium and the
T. adventitia, while a finely granular tissue with few elastic fibres forms
the bond of union between them. As we proceed from the very
smallest to the small arteries, the number of muscular fibres becomes
so great as to form a well-marked fibrous ring of non-striped muscle, in
which there is comparatively little connective tissue. In the large
arteries the amount of connective tissue is considerably increased, and
between the layers of fine connective tissue numerous (as many as
50) thick, elastic fibrous or fenestrated laminoe are concentrically
arranged.

A few non-striped fibres lie scattered amongst these, and some of
them are arranged transversely, while a few have an oblique or longi-
tudinal direction.

The first part of the aorta and pulmonary artery, and the retinal arteries are
devoid of muscle. The descending aorta, common iliac, and popliteal have longi-
tudinal fibres between the transverse ones. Longitudinal bundles lying inside the
media occur in the renal, splenic, and internal spermatic arteries. Longitudinal
bundles occur both on the outer and inner surfaces of the umbilical arteries, which
are very muscular.

(3.) The Tunica adventitia, or outer coat, in the smallest arteries
consists of a structureless membrane with a few connective tissue
corpuscles attached to it ; in somewhat larger arteries there is a layer
of fine fibrous elastic tissue mixed with bundles of fibrillar connective
tissue ((/). In arteries of middle size, and in the largest arteries the
chief mass consists of bundles of fibrillar connective tissue containing
connective tissue corpuscles. The bundles cross each other in a variety
of directions, and fat cells often lie between them. Next the media
there are numerous fibrous or fenestrated elastic lamellae. In medium
sized and small arteries the elastic tissue next the media takes the
form of an independent elastic membrane (Henle's external elastic

122

STRUCTURE OF CAPILLARIES.

membrane). Bundles of non-striped muscle, arranged longitudinally,

occur in the adventitia of
the arteries of the penis,
and in the renal, splenic,
spermatic, iliac, hypogas-
tric, and superior mesen-
teric arteries.

II. The Capillaries, while
retaining their diameter,
divide and reunite so as
to form net-works, whose
shape and arrangement
differ considerably in dif-
ferent tissues. The diame-
ter of the capillaries varies
considerably, but as a

Capillaries-The outlines of the endothelial cells g eneral rllle > ifc is Sllch as
marked off from each other by the cement
which is blackened by the action of silver
nitrate. The nuclei of the cells are obvious.

Fig. 41.

to admit freely a single
row of blood-corpuscles.
In the retina and muscle
the diameter is 5 6 JUL, and in bone-marrow, liver, and choroid
1020 /a. The tubes consist of a single layer of transparent, ex-
cessively thin nucleated endothelial cells joined to each other by their
margins (Hoyer, Auerbach, Eberth, Aeby, 1865).

[The nuclei contain a Avell-marked intra-nuclear plexus of fibrils,
like other nuclei.] The cells are more fusiform in the smaller capil-
laries and more polygonal in the larger. The body of the cells
presents the characters of very faintly refractive protoplasm, but it is
doubtful whether the body of the cell is endowed with the property of
contractility.

Action of Silver Nitrate. If a dilute solution (| per cent.) of
silver nitrate be injected into the blood-vessels, the cement substance
of the epithelium [and of the muscular fibres as well] is revealed by
the presence of the black " silver-lines" The blackened cement sub-
stance shows little specks and large black slits at different points.
It is not certain whether these are actual holes (J. Arnold) through
which colourless corpuscles may pass out of the vessels, or are merely
larger accumulations of the cement substance.

[Arnold called these small areas in the black silver lines when they were large
stomata, and when small stigmata. They are most numerous after venous
congestion, and after the disturbances which follow inflammation of a part
(Cohnheim, Winiwarter). They are not always present. The existence of cement
substance between the cells may also be inferred from the fact that indigo-

STRUCTURE OF VEINS.

123

sulphate of soda is deposited in it (Thoma), and particles of cinnabar and China
ink are fixed in it, when these substances are injected into the blood (Foa).]

Fine anastomosing fibrils derived from non-medullated NERVES
terminate in small end-buds in relation with the capillary wall;
ganglia in connection with capillary nerves occur only in the region
of the sympathetic (Bremer and Waldeyer).

[If a capillary is examined in a perfectly fresh condition (while
living) and without the addition of any reagent, it is impossible to
make out any line of demarcation between adjacent cells owing to
the uniform refractive index of the entire wall of the tube.]

The small vessels next in size to the capillaries and continuous
with them have -a completely
structureless covering in addition
to the eudothelium.

III. The Veins are generally
distinguished from the arteries by
their lumen being under than the
lumen of the corresponding
arteries; their walls are thinner
on account of the smaller amount
of non-striped muscle and elastic
tissue (the non-striped muscle is
not unfrequently arranged longi-
tudinally in veins). They are
also more extensile (with the same
strain). The adventitia is usually
the thickest coat.

The occurrence of valves is
limited to the veins of certain
areas. (1.) The inttma consists
of a layer of shorter and broader
endothelial cells, under which in
the smallest veins there is a
structureless elastic membrane,
sub-epithelial layer, which is fibrous
in veins somewhat larger in size,
but in all cases is thinner than in
the arteries. In large veins it
may assume the characters of a
fenestrated membrane, which is

Fig. 42.

Longitudinal section of a vein at the
level of a valve a, hyaline layer of
the internal coat; b, elastic lamina;
c, groups of smooth muscular fibres
divided transversely; d, longitudinal
muscular fibres in the adventitia.

double in some parts of the

crural and iliac veins. Isolated muscular fibres exist in the intima

of the femoral and popliteal veins.

124 STRUCTURE OF VEINS.

(2.) The media of the larger veins consists of alternate layers of
elastic and muscular tissue united to each by a considerable amount of
connective tissue, but this coat is always thinner than in the corres-
ponding arteries. This coat diminishes in the following order in
the following vessels popliteal, veins of the lower extremity, veins
of the upper extremity, superior mesenteric, other abdominal veins,
hepatic, pulmonary, and coronary veins. The following veins contain
no muscle veins of bone, central nervous system, and its membranes,
retina, the superior cava, with the large trunks that open into it,
the upper part of the inferior cava. Of course, in these cases, the
media is very thin. In the smallest veins the media is formed of
fine connective tissue, with very few muscular fibres scattered in
the inner part.

(3.) The adventilia is thicker than that of the corresponding
arteries; it contains much connective tissue usually arranged longi-
tudinally, and not much elastic tissue. Longitudinally arranged
muscular fibres occur in some veins (renal, portal, inferior cava near
the liver, veins of the lower extremities). The valves consist of
fine fibrillar connective tissue with branched cells. An elastic net-
work exists on their convex surface, and both surfaces are covered
by endothelium. The valves contain many muscular fibres (Fig. 42).
[Ranvier has shown that the shape of the epithelial cells covering
the two surfaces of the valves differs. On the side over which the
blood passes, they are more elongated than on the cardiac side of
the valve, where the long axes of the cell are placed transversely.]

The sinuses of the dura mater are spaces covered with endothelium. The spaces
are either duplicatures of the membrane, or channels in the substance of the tissue
itself.

Cavernous spaces we may imagine to arise by numerous divisions and anasto-
moses of tolerably large veins of unequal calibre. The vascular wall appears to
be much perforated and like a sponge, the internal space being traversed by threads
and strands of tissue, which are covered with endothelium on their surfaces, that
are in contact with the blood. The surrounding wall consists of connective tissue
which is often very tough, as in the corpus cavernosum, and it not unfrequently
contains non-striped muscle.

Cavernous Formations of an analogous nature on arteries, are the
carotid-gland of the frog, and a similar structure on the pulmonary
arteries and aorta of the turtle, and the coccygeal-gland of man (Luschka).
This structure is richly supplied with sympathetic nerve-fibres, and is a
convoluted mass of ampullated or fusiform dilatations of the middle
sacral artery (Arnold), surrounded and permeated by non-striped
muscle (Eberth).

Vasa Vasorum. [These are small vessels which nourish the coats of the
arteries and veins. They arise from one part of a vessel and enter the walls of

PHYSICAL PROPERTIES OF THE BLOOD-VESSELS. 125

the same vessel, or another at a lower level. They break up chiefly in the outer
coat, and none enter the inner coat.] In structure they resemble other small
blood-vessels, and the blood circulating in the arterial or venous wall is returned
by small veins.

Intercellular blood-channels. Intercellular blood-channels of narrow calibre
and without walls occur in the granulation tissue of healing wounds. At first
blood-plasma alone is found between the formative cells, but afterwards the blood-
current forces blood-corpuscles through the channels. The first blood-vessels in
the developing chick are formed in a similar way from the formative cells of the
mesoblast.

Properties of the Blood-Vessels. The larger blood-vessels are
cylindrical tubes composed of several layers of various tissues, more
especially elastic tissue and plain muscular fibres, and the whole is lined
by a smooth layer of epithelium. One of the most important properties
is the CONTRACTILITY of the vascular wall, in virtue of which the
blood-vessel becomes contracted, so that the calibre of the vessel and,
therefore, the supply of blood to a part are altered. The contractility
is due to the plain muscular fibres which are, for the most part,
arranged circularly. It is most marked in the small arteries, and of
course is absent where no muscular tissue occurs. The amount and
intensity of the contraction depend upon the development of the
muscular tissue ; in fact, the two go hand-in-hand. [If an artery be
exposed in the living body it soon contracts under the stimulus of the
atmosphere (J. Hunter) acting upon the muscular fibres.]

[Action of Alkalies and Acids on the Vascular System. Gaskell finds

that very dilute alkalies and acids have a remarkable effect on the blood-vessels
and also upon the heart. A very dilute solution of lactic acid (1 part to 10,000
parts of saline solution), passed through the blood-vessels of a frog, always enlarges
the calibre of the blood-vessels, while an alkaline solution (1 part sodium hydrate
to 10,000 or 20,000 parts saline solution) always diminishes their size, usually to
absolute closure, and indeed the artificial constriction of the blood-vessels may be
almost complete. These fluids are antagonistic to each other as far as regards
their action on the calibre of the arteries. Microscopic observations which con-
firmed these results, were also made on the blood-vessels of the mylohyoid muscle
of the frog. Dilute alkaline solutions act on the heart in the same way. After
a series of beats, the ventricle stops beating, the stand-still being in a state of con-
traction. Very dilute lactic acid causes the ventricle to stand still in the position
of complete relaxation. The action of the acid and alkali solutions are antagonistic
in their action on the ventricle. Gaskell attaches considerable importance to the
" tonic " and " atonic " conditions of the whole vascular system produced by very
dilute solutions of alkalies and acids respectively.]

That the capillaries undergo dilatation and contraction, owing to
variations in size of the protoplasmic elements of their walls, must be
admitted.

Strieker has described capillaries as "protoplasm in tubes," and observed that
they exhibited movements when stimulated in living animals. Golubew described
an active state of contraction of the capillary wall, but he regarded the nuclei as

126 PHYSICAL PROPERTIES OF THE BLOOD-VESSELS.

the parts which underwent change. Tarchanoff found that mechanical or electrical
stimulation caused a change in the shape and size of the nuclei, so that he regards
these as the actively contractile parts. [Severini also attaches great importance
to the contractility of the capillaries.] Strieker's observations were made on the
capillaries of tadpoles. These phenomena became less marked as the animal
became older. Rouget observed the same result in the capillaries of new-born
mammals. As the capillaries are excessively thin and delicate, and as they are
soft structures, it is obvious that the form of the individual cells must depend to a
considerable extent upon the degree to which the vessels are tilled with blood. In
vessels which are distended with blood the eudothelial cells ai-e flattened, but when
the capillaries are collapsed, they project more or less into the lumen of the vessel
(Reuaut).

[It is a well-known fact that the capillaries present great variations in their
diameter at different times. As these variations are usually accompanied by a
corresponding contraction or dilatation of the arterioles, it is usually assumed that
the variations in the diameter of the capillaries are due to differences of the pres-
sure within the capillaries themselves viz., to the elasticity of their walls. Every
one is agreed that the capillaries are very elastic, but the experiments of Roy and
Graham Brown show that they are contractile as well as elastic, and these
observers conclude that under normal conditions, it is by the contractility of the
capillary wall as a whole that the diameter of these vessels is changed, and to all
appearance their contractility is constantly in action. "The individual capillaries
(in all probability) contract or expand in accordance with the requirements of the
tissues through which they pass. The regulation of the vascular blood-flow is thus
more complete than is usually imagined" (Roy and Graham Brown).]

Physical Properties. Amongst the physical properties of the blood-
vessels, ELASTICITY is the most important ; their elasticity is small in
amount, i.e., they offer little resistance to any force applied to them so
as to distend or elongate them, but it is perfect in quality, i.e., the
blood-vessels rapidly regain their original size and form after the force
distending them is removed.

[The elasticity of the arteries is of the utmost importance in aiding the conversion
of the interrupted flow of the blood in the large arteries into a uniform flow in
the capillaries. E. H. Weber compared the elastic wall of the arteries with the
air in the air-chamber of a fire-engine. In both cases an elastic medium is acted
upon the air in the one case and the elastic tissue in the other which in turn
presses upon the fluid, propelling it onwards continually, while the action of the
pump or the heart, as the case may be, is intermittent.]

According to E. H. Weber, Volkmann, and Wertheim, the elongation of a blood-
vessel (and most moist tissues) is not proportional to the weight used to extend it,
the elongation being relatively less with a large weight than with a small one, so
that the curve of extension is nearly [or, at least, bears a certain relation to] a
hyperbola.

According to Wundt, we have not only to consider the extension produced at
first by the weight, but also the subsequent "elastic after-effect," which occurs
gradually. The elongation which occurs during the last few moments occurs so
slowly and so gradually that it is well to observe the effect by means of a magni-
fying lens. Variations from the general law occur to this extent, that if a certain
weight is exceeded, less extension, and, it may be, permanent elongation of the
artery not unfrequently occur. K. Bardelebeu found, especially in veins
elongated to 40 or 50 per cent, of their original length, that when the weight
employed increased by an equal amount each time, the elongation was proportional

THE PULSE. 127

to the square-root of the weight. This is apart from any elastic after-effect. Veins
may be extended to at least 50 per cent, of their length without passing the limit
of their elasticity.

[Roy has made careful experiments upon the elastic properties of the arterial
wall. A portion of an artery, so that it could be distended by any desired internal
pressure, was inclosed in a small vessel containing olive oil. The small vessel with
oil was arranged in the same way as in Fig. 33 for the heart. The variations of
the contents were recorded by means of a lever writing on a revolving cylinder.
The aorta and other large arteries were found to be most elastic and most distensible
at pressures corresponding more or less exactly to their normal blood-pressure,
while in veins the relation between internal pressure and the cubic capacity is very
different. In them the maximum of clistensibility occurs with pressures imme-
diately above zero. Speaking generally, the cubic capacity of an artery is greatly
increased by raising the intra-arterial tension, say from zero to about the normal
internal pressure which the artery sustains during life. Thus in the rabbit the
capacity of the aorta was quadrupled by raising the intra-arterial pressure from
zero to 2UO mm. Hg., while that of the carotid was more than six times as great
at that pressure as it was in the undistended condition. The pulmonary artery is
distinguished by its excessive elastic distensibility. Its capacity (rabbit) was
increased more than twelve times on raising the internal pressure from zero to
about 36 mm. Hg. Veins, on the other hand, are distinguished by the relatively
small increase in their cubic capacity produced by greatly raising the internal
pressure, so that the enormous changes in the capacity of the veins during life, are
due less to differences in the pressure than to the great differences in the quantity
of blood which they contain (Roy).]

Pathological. Interference with the nutrition of an artery alters its elasticity
[and that in cases where no structural changes can be found]. Marasmus pre-
ceding death causes the arteries to become wider than normal (Roy). Age also
influences their elasticity in some old people they become atheromatous and
even calcined. [The ratio of expansion of strips of the aortic wall to the weights
employed to stretch them, remains much the same from childhood up to a certain
age (Roy).]

Cohesion. Blood-vessels are endowed with a very large amount of
cohesion, in virtue of which they are able to resist even considerable
internal pressure without giving way. The carotid of a sheep is ruptured
only when fourteen times the usual pressure it is called upon to bear is
put upon it (Volkmann). A greater pressure is required to rupture a
vein than an artery with the same thickness of its wall.

66. The PulseHistorical.

Although the movement of the pulse in the superficially placed arteries was
known to the ancients, still the pulse, as it was affected by disease, was more
studied by the older physicians than the normal pulse. Hippocrates (460 to 377
B.C.) speaks of the former as o-^uyuos, while Herophilus (300 B.C.) contrasted the
normal pulse (TraX/uos) with the pulse of disease (o-^uyjuos). He lays special stress
upon the relative time occupied by the dilatation and contraction of the arterial
tube, and compares these phenomena with the notes of music. He established the
fact that the rhythm of the pulse varies in the newly-born, in the adult, and in
the aged. Further, he distinguished the size, fulness, quickness, and. frequency of
the pulse. Erasistratus (f280 B.C.), a contemporary of Herophilus, made correct

128

INSTRUMENTS FOR INVESTIGATING THE PULSE.

observations on the pulse-wave. He points out that the pulse occurs sooner in
arteries near the heart than in those placed further away from it, because the pulse
proceeding from the heart passes towards the periphery. Erasistratus placed a
caunula in the course of an artery, and he found that the pulse could still be felt
on the distal side of this point. Archigenes gave the name dicrotic pulse to a
condition which he had observed in febrile conditions. Galen (131 to 202 A.D. )
gave more exact details as to the relations of the dilatation and contraction of the
arteries during the movement of the pulse, and supplied much information on the
pulse-rhythm, and the influence of temperament, age, sex, period of the year,
climate, sleep and waking, cold and warm baths, on its rate and other qualities.
Cusanus (15C5) was the first person to count the pulse-beats with the aid of a
watch.

67. Instruments for Investigating the Pulse.

The individual phases of the movement of the pulse could only be
accurately investigated by the application of instruments to the arteries.

(1.) Poiseilille's BOX Pulse-Measurer (1829). An artery (Fig. 43, a, a) is
exposed and placed in an oblong box (K, K) rilled with an indifferent fluid. A
vertical tube with a scale attached communicates with the interior of the box.
The column of fluid undergoes a variation with every pulse-beat.

Fig. 43.

Poiseuille's pulse-measurer a, a, exposed artery ; K, K, the
box consisting of two pieces ; b, vertical tube, with scale
attached.

Fig. 44.

Xphygmometer of
HeVisson and
Chelius.

(2.) He"risson's Tubular Sphygmometer consisted of a glass-tube whose

lower end was covered with an elastic membrane (Fig. 44). The tube was partly
rilled with Hg. The membrane was placed over the position of a pulsating artery,
so that its beat caused a movement in the Hg. Chelius used a similar instrument,

MAREY'S SPHYGMOGRAPH. 129

and he succeeded with this instrument in showing the existence of the double-
beat (dicrotism) in the normal pulse (1850).

(3.) Vierordt's Sphygmograph (1855). In this, one of the earliest sphygmo-
graphs, Vierordt departed from the principle of a fluctuating fluid column, and
adopted the principle of the lever. Upon the artery rested a small pad, which
moved a complicated system of levers. At first he used a straw six inches long,
which rested on the artery. The point of one of the levers inscribed its movements
upon a revolving- cylinder. This instrument was soon discarded.

(4.) Marey's Sphygmograph consists of a combination of a lever
with an elastic spring. It consists of an elastic spring (Fig. 45, A)
fixed at one end, 2, free at the other end, and provided with an ivory
pad, y, which is pressed by the spring upon the radial artery. On
the upper surface of the pad there is a vertically-placed fine toothed
rod, k, which is pressed upon by a weak spring, e, so that its teeth
dove-tail with similar teeth in the small wheel, t, from whose axis
there projects a long, light, wooden lever, v, running nearly parallel
with the elastic spring. This lever has a fine style at its free-end, s,
which writes upon a smoked plate, P, moved by clock-work, U, in front
of the style. Marey's instrument, as improved by Mahomed and others,
has been very largely used.

*

V

J

P

JH

S

d^=. ^ . r^

u

Fig. 45.

Scheme of Marey's sphygmograph A, spring with ivory pad, y, which rests on
the artery ; e, weak spring pressing k into t ; v, writing lever ; P, piece of
smoked glass or paper moved by clock-work, U ; H, screw to limit excursion
of A ; s, arrangement for fixing the instrument to the arm of the patient,

[Its more complete form, as in Fig. 46, where it is shown applied to the arm,
consists of (1.) a steel spring, A, which is provided with a pad resting on the
artery, and moves with each movement of the artery; (2.) the lever, C, which
records the movement of the artery and spring in a magnified form on the smoked
paper, G ; (3.) an arrangement, L, whereby the exact pressure exerted upon the
artery is indicated on the dial, M (Mahomed) ; (4.) the clock-work, H, which
moves the smoked paper, G, at a uniform rate ; (5.) a frame-work to which the
various parts of the instrument are attached, and by means of which the instru-
ment is fastened to the arm by the straps, K, K (Byrom Bramwell).

[Application. In applying the sphygmograph, cause the patient to seat himself
beside a low table, and place his arm on the double-inclined plane (Fig. 46). In
the newer form of instrument, the lid of the box is so arranged as to unfold to
make this support. The fingers ought to be semi-flexed. Mark the position of
the radial artery with ink. See that the clock-work is wound up, and apply the

9

130

MAREY'S SPHYGMOGRAPH.

ivory pad exactly over the radial artery where it lies upon the radius, fixing it to
the arm by the non -elastic straps, K, K (Fig. 46). Fix the slide holding the smoked
paper in position. The best paper to use is that with a very smooth surface
(albuminised or enamelled card) smoked over the flame of a turpentine lamp, or
over a piece of burning camphor. The writing-style is so arranged as to write
upon the smoked paper with the least possible friction. The most important part

Fig. 46.

Marey's improved sphygmograph as used when a tracing is taken A, steel
spring ; B, first lever ; C, writing lever ; C', its free writing end ; D, screw
for bringing B in contact with C ; G, slide with smoked paper ; H, clock-
work ; L, screw for increasing the pressure ; M, dial indicating the amount of
pressure ; K. K, straps for fixing the instrument to the arm, and the arm to
the double-inclined plane or support (Byrom Bramwell).

of the process is to regulate the pressure exerted upon the artery by means of the
milled head, L. This must be determined for each pulse, but the rule is to
graduate the pressure until the greatest amplitude of movement of the lever is
obtained. Set the clock-work going, and a tracing is obtained, which must be
" fixed " by dipping it in a rapidly drying varnish c.y., photographic. In every
case scratch on the tracing with a needle the name, date, and amount of pressure
employed.]

Fig. 47.

A 1

Fig. 48.

- 47. Scheme showing the essential part of the instrument wlien in workincj
order i.e., the turned up knife-edge, B", of the short lever in contact with
the writing lever, C. Every movement of the steel spring at A" i.e., the
artery will in this position be communicated to the writing lever.

[Fig. 48. Scheme showing the essential parts of the instrument after increase of
the pressure. The knife-edge, B", is no longer in contact with the writing
lever, and the movements of the steel spring, A" i.e., the artery are no
longer communicated to it. In order to put the instrument into working
order, the knife-edge, B", must be raised to the position indicated by the
dotted lines. This is effected by means of the screw, D (Byrom Bramwell).]

DUDGEON S SPHYGMOGRAPH.

131

[(5.) Dudgeon's Sphygmograph. This is a most convenient form of
sphygmograph. Fig. 49 shows its actual size.

Fig. 49. Dudgeon's sphygmograph.

The instrument after being carefully adjusted upon the radial artery
is kept in position by an inelastic strap. The pressure of the spring
is regulated by the eccentric wheel to any amount from 1 to 5 ounces.

Fig. 50. Mode of applying Dudgeon's sphygmograph.

132

BRONDGEEST'S PANSPHYGMOGRAPH.

As in other instruments, the tracing paper is moved in front of the
writing-needle by means of clock-work. The writing-levers are so
adjusted that the movements of the artery are magnified fifty times.]

[Fig. 51 is a sphygmogram taken
with this instrument from a
healthy individual. It represents
a perfect tracing a. the vertical
upward, systolic or percussion
wave ; b, apex ; c, on the
descent ; d, first tidal or pre-
dicrotic wave; e, aortic notch ;
Fig. 51. Sphygmogram pressure 2 oz. /, dicrotic wave (Dudgeon).]

(6.) Marey's Tambours are also employed for registering the move-
ments of the pulse. They are used in the same way as the pansphygmograph
of Brondgeest. Fig. 52 shows their arrangement. Two pairs of metallic
cups (S, S and S', S', Upham's capsules) are pierced in the middle by

Z'

Fig. 52.

Scheme of Brondgeest's sphygmograph, on the principle of Upham and Marey's
tambours S, S' , receiving and recording (S, S') tambours with writing -levers,
Z and Z'; K, K', conducting tubes : p over heart, p' over a distant artery.
This illustration also shows the principle of Marey's cardiograph.

thin metal tubes, whose free-ends are connected with caoutchouc tubes,
K and K'. All the four metallic vessels are covered with an elastic
membrane. On S and S' are fixed two knob-like pads, p and p',
which are applied to the pulsating arteries, and the metal arcs, B and

LANDOIS ANGIOGRAPH.

133

B', retain them in position. On the other tambours are arranged the
writing levers, Z and 71. Pressure on the one tambour necessarily
compresses the air and makes the other, with which it is connected,
expand, so as to move the writing-lever. This arrangement does not
give absolutely exact results ; still, it is very easily used and is con-
venient. In Fig. 52 a double
arrangement is shown, where-
by one instrument, B, may
be placed over the heart, and
the other, B', on a distant
artery.

Landois" Angiograph. To
a basal plate, G, G, are fixed
two upright supports, p, which
carry between them at their
upper part the movable lever,
d, r, carrying a rod bearing a
pad, e, directed downwards,
which rests on the pulse.
The short arm carries a coun-
terpoise, d, so as exactly to
balance the long arm. The
long arm has fixed to it at r
a vertical rod provided with
teeth, h, which is pressed
against a toothed wheel firmly
fixed on the axis of the very
light writing-lever, e /, which
is supported between two up-
rights, q, fixed to the opposite
end of the basal plate, G, G.
The writing-lever is equilibri-
ated by means of a light
weight. The writing-needle,
k, is fixed by a joint to e, and
it writes on the plate, /. The
first - mentioned lever, d, r,
carries a shallow plate, Q, just
above the pad, into which
weights may be put to weight
the pulse. In this instrument
the weight can be measured
and varied] the writing-lever moves vertically and not in a curve

134

CHARACTERS OF A PULSE-CURVE.

as iii Marey's apparatus, which greatly facilitates the measuring of
the curves. (Fig. 53.)

Other sphygmographs are used, botli in this country and abroad, including that
of Sommerbrodt, which is a complicated form of Marey's sphygmograph, and
those of Pond and Mach. In choosing a sphygmograph, that instrument is to be
preferred which yields a curve corresponding most closely with the variations of

the pressure within the artery, in
which the resistance of the instrument
is small, which gives the largest curve,
and in which the part in contact with
the artery is not greatly displaced
from its position of equilibrium
(Mach).

Characters of a Pulse-Curve.
In every pulse-curve SPHYGMO
GRAM or ARTERIOGRAM we can
distinguish the ascending part
(ascent) of the curve, the apex,
and the descending part (descent).
Secondary elevations scarcely
ever occur in the ascent, which
is usually represented by a
straight line, while they occur
constantly in the descent. Such
elevations occurring in the de-
scent are called catacrotic, and
those in the ascent, anacrotic
(Landois). When the recoil
elevation or dicrotic wave occurs
in a well-marked form in the
descent, the pulse is said to be
dicrotic, and when it occurs twice,
tricrotic.

Measuring Pulse-Curves. If the

smoked surface on which the tracing
is inscribed is moved at a uniform
rate by means of the clock-work,
then the height and length of the
curve are measured by means of an
ordinary rule. If we know the rate
at which the paper was moved, then
it is easy to calculate the duration of
any event in the curve. For exact
observation a low -power microscope
with a micrometer in the eye-piece
should be used,
fixing the tracings see p, 130.

Fig. 54.

Pulse-curves of the carotid, radial, and
posterial tibial arteries of a healthy
student, obtained by Landois' angio-
graph writing upon a plate attached
to a vibrating tuning-fork. Each
double vibration corresponds to
0-01613 sec.

For the method of smoking the paper and

LANDOIS' GAS-SPHYGMOSCOPE.

135

It is very convenient to write the curve upon a plate of glass fixed
to a tuning-fork kept in vibration. Every part of the curve shows
little elevations (whose rate of vibration is known beforehand). All
that is required is to count the number of vibrations in order to
ascertain the duration of any part of the curve.

Fig. 54 was taken in this way from (A) the carotid, (B) the radial,
and (C) the posterior tibial arteries of a healthy student. The results

are :

1-2,
1-3,

1-4,
1-5,

Carotid.

7
17

23-5
56

Radial.

7

16
22-5
39

Posterior
TibiaL

8
19
28
49

This method has also been used for the registration of other physiological
processes e.g., contraction of muscle.

Landois Gas-SphyglUOSCOpe. A superficially placed artery communicates its
movements to the overlying skin, and also to any freely movable body in contact
with the skin. In this instrument (Fig. 55) a thin layer of air over the pulsating
artery, a, is enclosed by means of a thin piece of metal, which ia so adjusted that
its concave side forms a tunnel of air over the artery. The narrow space between
the metallic wall, b, and the skin, a, is filled with ordinary gas, one end of the
metal shield being connected by means of a tube, y, with the gas-supply, while to
the other end there is attached by means of a short piece of caoutchouc, x, q, a
bent glass-tube, t, with a very small aperture which acts as a gas-burner. The
gas is allowed to flow through the apparatus at a low pressure, and is so regulated
that the flame, v, is only a few millimetres in height. The flame rises isochron-
ously with every pulse-beat, and the dicrotic beat in the normal pulse is quite
observable.

Fig. 55.

Landois' gas-sphygmoscope a, skin over artery ; b, metal plate ; p, y, gas ;
x, q, caoutchouc tube attaching glass gas-burner, t to b.

Czermak photographed a beam of light set in motion by the movements of the
pulse.

Hsemautography. Expose a large artery of an animal, and divide it so that
the stream of blood issuing from it strikes against a piece of paper drawn in front

136

THE PULSE-CURVE.

of the blood-stream. A curve (Fig

Fig. 56.

Htemautographic curve of the pos-
terior tibial artery of a large dog
P, primary pulse wave ; R,
dicrotic or recoil wave ; e, e,
elevations due to elasticity.

56), is obtained which corresponds very closely
with the pulse-tracing obtained from a normal
artery. In addition to the primary wave, P,
there is a distinct " recoil-elevation," or
dicrotic wave, R, and slight vibrations, c, e,
due to variations in the elasticity of the
arterial wall. The interest which attaches to
a curve obtained in this way is, that it shows
the movements to occur in the blood itself,
and these movements to be communicated
as waves to the arterial wall. By estimat-
ing the amount of blood in the various parts
of the ciirve we obtain a knowledge of the
amount of blood discharged by the divided
artery during the systole and diastole (i.e.,
the narrowing and dilatation) of the artery
the ratio is 7:10. Thus in the unit of time,
during arterial dilatation rather more than
twice as much blood flows out as happens
during arterial contraction.

Microphone- Fix a small piece of wax
over the radial artery, and to it attach a very
fine vertical wire which is brought into con-
tact with the charcoal of a microphone held
over the artery. The primary pulse wave
and dicrotic wave are distinctly heard in a
telephone brought into connection with the
microphone (Landois). All these methods
are well suited for demonstrating the pulse,
but for accuracy resort must be had to some
form of recording instrument.

68. The Pulse-Curve or Sphygmogram.

A sphygmogram consists of several curves, each one of which corre-
sponds with a beat of the heart. Each pulse-curve consists of (1.) the
ascending part which occurs during the dilatation (diastole) of the
artery; (2.) the apex, (P in Fig. 58 and b in Fig. 57); (3.) the de-
scending part, corresponding to the contraction (systole) of the artery.
The most noticeable peculiarity of the pulse-curve is the existence
of tico completely distinct elevations occurring in the descent. The more
distinct of the two occurs as a well-marked elevation about the
middle of the descent (R in Fig. 58 and / in Fig. 57); it is called the
DICROTIC WAVE, or with reference to its mode of origin, the " recoil
wave" The ascent, also called up-stroke or percussion stroke
(Mahomed), in a normal sphygmogram, is nearly vertical, while the
apex of the percussion stroke is usually pointed.

[In Fig. 57, each part of the curve between the base of one up-

ORIGIN AND CHARACTERS OF THE DICROTIC WAVE. 137

stroke and the base of the next up-stroke corresponds to a beat of the
heart, so that this figure
shows five heart-beats and
part of a sixth. The part,
a, b = the ascent, i, the
apex of the up-stroke, and
b to h, the descent, with a
curve, d, called the first

tidal or predicrotic wave, Sphygmogram of radial artery pressure 2 oz.
e, an angle or notch, the
aortic notch, /, a second elevation, called the dicrotic wave, </, a slight
curve, sometimes called the second tidal wave. The descent is con-
tinued to h, where the ascent of the next heart-beat begins.]

I. Origin and Characters of the Dicrotic Wave,

The dicrotic or recoil wave, which is always present in a normal
pulse, is caused thus : During the ventricular systole a mass of blood
is propelled into the already full aorta, whereby a positive wave is
rapidly transmitted from the aorta throughout the arterial system, even
to the smallest arterioles, in which this primary wav. is extinguished. As
soon as the semi-lunar valves are closed, and no more blood flows into
the arterial system, the arteries which were previously distended by the
mass of blood suddenly thrown into them, recoil or contract, so that
in virtue of the elasticity (and contractility) of their walls, they
exert a counter-pressure upon the column of blood, and thus the blood
is forced onwards. There is a free passage for it towards the periphery,
but towards the centre (heart) it impinges upon the already closed
semi-lunar valves. This developes a new positive wave, which is pro-
pagated peripherally through the arteries, where it disappears in their
finest branches. In those cases where there is sufficient time for the
complete development of the pulse-curve (as in the short course of the
carotids, and in the arteries of the upper arm, but not in those of the
lower extremity, on account of their length), a second wave of reflec-
tion may be caused in exactly the same way as the first.

Just as the pulse occurs later in the more peripherally placed
arteries than in those near the heart, so the secondary wave reflected
from the closed aortic valves must appear later in the peripheral
arteries. Both kinds of waves, the primary pulse wave, the secondary,
and eventually even the tertiary reflected wave arise in the same place,
and take the same course, and the longer the course they have to
travel to any part of the arterial system, the later they arrive at their
destination.

138

CHARACTERS OF THE DICROTIC WAVE.

The following points regarding the dicrotic wave have been ascer-
tained experimentally :

xn

XIII

Fig. 58.

I, II, III, Sphygrnogram of carotid artery ; IV, axillary ; V to IX, radial ;
X, dicrotic radial pulse ; XI, XII, crural ; XIII, posterior tibial ; XIV,
XV, pedal. In all the curves P, indicates apex ; R, dicrotic wave ; e, e,
elevations due to elasticity; K, elevation caused by closure of the semi-lunar
valves of the aorta.

(1.) The dicrotic wave occurs later in the descending part of the

ORIGIN AND CHARACTERISTICS OF THE ELASTIC ELEVATIONS. 1 39

curve, the further the artery experimented upon is distant from the
heart (Landois, 1863). Compare the curves, Fig. 54, p. 134.

The shortest accessible course is that of the carotid : where the dicrotic wave
reaches its maximum 0'35 to 0'37 sec. after the beginning of the pulse. In the
upper extremity the apex of the dicrotic wave is 0'36 to 0'38 to 0'40 sec. after
the beginning of the pulse-beat. The longest course is that of the arteries of the
lower extremity. The apex of the dicrotic wave occurs 0'45 to 0'52 to 0'59 sec.
after the base of the curve. It varies with the height of the individual.

(2.) The dicrotic elevation in the descent is lower (Naumann), and
is less distinct (Landois), the further the artery is situated from the
heart. This is just what one would expect viz., the longer the
distance which the wave has to travel the less distinct it must become.

(3). It is more pronounced in a pulse where the primary pulse-wave
is short and energetic (Marey, Landois). It is greatest relatively
when the systole of the heart is short and energetic.

(4.) It is greater the lower the tension or pressure of the blood
within the arteries (Marey, Landois), [and is best developed in a soft
pulse]. In Fig. 58, IX and X were obtained when the tension of the
arterial wall was low; V and VI, medium; and VII with high tension.

Conditions Influencing Arterial Tension. It is diminished at the beginning
of inspiration, by haemorrhage, stoppage of the heart, heat, an elevated position of
parts of the body ; it is increased at the beginning of expiration by accelerated
action of the heart, stimulation of vaso-motor nerves, diminished outflow of blood
at the periphery, and by inflammatory congestion (Knecht) ; further, by certain
poisons, as lead, amyl nitrite ; compression of other large arterial trunks, action of
cold and electricity on the small cutaneous vessels, and by impeded outflow of venous
blood. When a large arterial trunk is exposed the stimulation of the air causes
it to contract, resulting in an increased tension within the vessel. In many
diseased conditions the arterial tension is greatly increased [e.g., in Bright'a
disease, where the kidney is contracted ("granular"), and where the left ventricle
is hypertrophied].

In all these conditions increased arterial tension is indicated by the dicrotic
wave being less high and less distinct, while with diminished arterial tension it is
a larger and apparently more independent elevation. Moens has shown that the
time between the primary elevation and the dicrotic wave increases with increase
in the diameter of the tube, with diminution of its thickness, and when ita
coefficient of elasticity diminishes.

II. Origin and Characteristics of the Elastic

Elevations.

Besides the dicrotic wave, a number of small less-marked elevations
occur in the course of the descent in a sphygmogram (Fig. 58, e, e).
These elevations are caused by the elastic tube being thrown into
vibrations by the rapid energetic pulse- wave, just as an elastic mem-
brane vibrates when it is suddenly stretched. The artery also executes

140 DICROTIC PULSE.

vibratory movements when it passes suddenly from the distended to
the relaxed condition. These small elevations in the pulse-curve,
caused by the elastic vibrations of the arterial wall, are called " elastic
elevations " by Landois.

(1.) The elastic vibrations increase in number in one and the same
artery with the degree of tension of the elastic arterial wall. A very
high tension occurs in the cold stage of intermittent fever, in which
case these elevations are well marked. (2.) If the tension of the
arterial wall be greatly diminished these elevations may disappear,
so that while^diminished tension favours the production of the dicrotic
wave, it acts in the opposite way with reference to the " elastic
elevations." ,- [(3.) In diseases of the arterial walls affecting their
elasticity, these elevations are either greatly diminished or entirely
abolished. (4.) The farther the arteries are distant from the heart,
the higher are their elevations. (5.) When the mean pressure within
the arteries is increased by preventing the outflow of blood from
them, the elastic vibrations are higher and nearer the apex of the
curve. (6.) They vary in number and length in the pulse-curves
obtained from different arteries of the body.

When the arm is held in an upright position, after rive minutes the blood-vessels
empty themselves, and collapse, while the elasticity of the arteries is diminished.

69. Dicrotic Pulse.

Sometimes during fever, especially when the temperature is high, a dicrotic pulse
may be felt, each pulse-beat, as it were, being composed of two beats (Fig. 58, X),

Fig. 59.
Pulsus dicrotus P. caprizans ; P. monocrotus. '

one beat being large and the other small, and more like an after-beat. Both
beats correspond to one beat of the heart. The two beats are quite distinguishable
by the touch. The phenomenon is only an exaggerated condition of what occurs

CHARACTERS OF THE PULSE. 141

in a normal pulse. The sensible second beat is nothing more than the greatly
increased dicrotic elevation, which, under ordinary conditions, is not felt by the
finger.

Conditions. The occurrence of a dicrotic pulse is favoured (1) by a short
primary pulse-wave, as in fevers, where the heart beats rapidly ; (2) by a
diminished tension within the arterial system. A short systole and diminished
arterial blood-pressure are the most favourable conditions for causing a dicrotic
pulse. The double-beat may be felt only at certain parts of the arterial system,
whilst at other parts only a single beat is felt. A favourite site is the radial
artery of one or the other side, where conditions favourable to its occurrence appear
to exist. This seems to be due to a local diminution of the blood-pressure in this
area, owing to the paralysis of its vaso-motor nerves (Landois). If the tension be
increased by compressing other large arterial trunks or the veins of the part, the
double-beat becomes a simple pulse-beat. The dicrotic pulse in fever seems to be
due to the increased temperature (39 to 40C.), whereby the artery is more dis-
tended, and the heart-beat is shorter and more prompt (Riegel).

(3.) It is absolutely necessary that the elasticity of the arterial wall be normal.
The dicrotic pulse does not occur in old persons with atheromatous arteries
(Landois). In Fig. 59, A, B, C, we observe the gradual passage of the normal
radial curve, A, into the dicrotic beat, B, C, where the dicrotic wave, r, appears
as an independent elevation. If the frequency of the pulse increases more and
more in fever, the next following pulse-beat may occur in the ascending part of
the dicrotic wave, D, E, F, and it may even occur close to the apex, G (P.
caprizans). If the next following beat occurs in the depression, i, between the
primary elevation, p, and the dicrotic elevation, r, the latter entirely dis-
appears, and the curves, H, assume what Landois calls the " monocrotic " type.

70. Characters of the Pulse.

1. Pulsus Frequens and Rarus.

Frequency. According as a greater or less number of beats occurs in a given
time, e.g., per minute, the pulse is said to be frequent or rare. The normal
rate, in man=71 per minute, and somewhat more in the female ; in fever it may
exceed 120 (250 have been counted by Bowles), while in other diseases it may fall
to 40, and even 10 to 15 (cle Haen), 17 (Hartog), and 14 (Cornil) ; but such
cases are rare, and are probably due to an affection of the cardiac nerves. The
frequency of the pulse is usually increased when the respirations are deeper, but
not more numerous, i.e., rapid shallow respirations do not affect the frequency of
the pulse, but deep respirations do (Knoll).

2. Pulsus Celer and Tardus.

Celerity or Rapidity. If the pulse-wave is developed so that the distension of
the artery slowly reaches its height and the relaxation also takes place gradually,
we have the p. tardus or slow pulse, the opposite condition gives rise to the p.
celer or quick pulse. The rapidity of the pulse is increased by quick action of the
heart, power of expansion of the arterial walls, easy efflux of blood owing to the
dilatation of the small arteries, and by nearness to the heart. [The quickness
has reference to -a single pulse-beat, the frequency to a number of beats.] In a
quick pulse, the curve is high and the angle at the apex is acute, while in a slow
pulse the ascent is low and the angle at the apex is large.

142

CONDITIONS AFFECTING THE PULSE-RATE.

3. Conditions affecting the Pulse-Rate.

Frequency in Health- In man the normal pulse-rate = 71 to 72 beats per
minute, in the female about 80. In some individuals the pulse-rate may be higher
(90 to 100), in others lower (50), and such a fact must be borne in mind. The
following conditions influence it

(a.) Age.

Newly Born,

1 Year,

2 Years,

3

4

5
10

Beats per
Minute.

130 to 140

120 to 130

105

100
97

94 to 90
about 90

10 to 15 Years,

15 to 20 ,,

20 to 25 ,,

25 to 50

60

SO

80 to 90

Beats per
Minute.

. 78

. 70

. 70

. 70

. 74

. 79

over 80

(b.) The length Of the body has a certain relation to the frequency of the
pulse. The following results have been obtained by Czarnecki from the formula?
of Volkmann and Kameaux

Length of Body
in 10 Ctm.

80 to 90 .

90 to 100 .

100 to 110 .

110 to 120 .

120 to 130 .
130 to 140

Pulse
Calculated. Observed.

Length of Body
in 10 Ctm.

. 90

103

140 to 150 .

. 86

91

150 to 160 .

. 81

87

160 to 170 .

. 78

84

170 to 180 .

. 75

78

above ISO .

. 72

76

Pulse.
Calculated. Observed.

69
67
65
63
60

74
68
65
64
60

(c.) The pulse-rate is increased by muscular activity, by every increase of the arterial
blood-pressure, by taking of food, increased temperature, painful sensations, and by
psychical disturbances. [Increased heat or fever (Pyrexia) increases the frequency,
and as a rule the increase varies with the height of the temperature. Dr. Aitken
states that an increase of the temperature of 1 F. above 98 F. corresponds with an
increase of ten pulse-beats per minute ; thus,

Temp. F.
no

'O .....

99

100 . . .

101

102

This is merely an approximate estimate.] It is more frequent when a person is
standing than when he lies down. Music accelerates the pulse and increases the
blood-pressure in dogs and men (Dogiel). Exposure to increased barometric
pressure diminishes the frequency.

The variation of the. pulse-rate during the day 3 to 6 a.m. =61 beats ; 8 to 11
a.m. =74. It then falls towards 2 p.m. ; towards 3 (at dinner-time) another
increase takes place and goes on until 6 to 8 p.m., =70; and it falls until mid-
night =54. It then rises again towards 2 a.m., when it soon falls again, and
afterwards rises as before towards 3 to 6 a.m.

Pulse-Rate.

Temp. F.

Pulse-Rate.

60

103

. 110

70

104

. 120

80

105

. 130

90

106

. 140

100

4. Variations in the Pulse-Rhythm.

On applying the fingers to the normal pulse we feel beat after beat occurring
at apparently equal intervals. Sometimes in a normal series a beat is omitted
= pulsus intermittens, or intermittent pulse; at other times the beats become

VARIATIONS IN THE STRENGTH, TENSION, AND VOLUME OF THE PULSE. 143

smaller and smaller, and after a certain time begin as large as before = P. myurus.
When an extra beat is intercalated in a normal series = P. intercurrens. The
regular alternation of a high and a low beat = P. alternans (Traube). In the
P. bigeminus of Traube the beats occur in pairs, so that there is a longer pause

Fig. 60.
Pulsus alternans.

after every two beats. Traube found that lie could produce this form of pulse in
curarised dogs by stopping the artificial respiration for a long time. The P. frige-
minus and quadrigcminus occur in the same way, but the irregularities occur after
every third and fourth beat. Knoll found that in animals such irregularities of
the pulse were apt to occur, as well as great irregularity in the rhythm generally,
when there is great resistance to the circulation, and consequently the heart has great
demands upon its energy. The same occurs in man, when an improper relation
exists between the force of the cardiac muscle and the work it has to do (Riegel).
Complete irregularity of the heart's action is called arhythmia corclis.

71. Variations in the Strength, Tension, and
Volume of the Pulse.

The relative strength of the pulse (p. fortis and debilis), i.e., whether the pulse
is strong or ivealc, is estimated by the weight which the pulse is able to raise. A
sphygmograph, provided with an index indicating the amount of pressure exerted
upon the spring pressing npon the artery, may be used (Fig. 46). In this case,
as soon as the pressure exerted upon the artery overcomes the pulse-beat, the
lever ceases to move. The weight employed indicates the strength of the puke.
[The ringer may be, and generally is, used. The finger is pressed upon the
artery until the pulse-beat in the artery beyond the point of pressure is obliterated.
In health it requires a pressure of several ounces to do this. Handfield Jones uses
a SPHYGMOMETER for this purpose. It is constructed like a cylindrical letter-
weight, and the pressure is exerted by means of a spiral spring which has been
carefully graduated.] The pulse is hard or soft when the artery, according to the
mean blood pressure, gives a feeling of greater or less resistance to the finger, and
this quite independent of the energy of the individual pulse-beats (P. durus and
mollis).

In estimating the tension of the artery and the pulse, i.e., whether it is hard
or soft, it is important to observe whether the artery has this quality only during
the pulse- wave, i.e., if it is hard during diastole, or whether it is hard or soft
during the period of rest of the arterial wall. All arteries are harder and less
compressible during the pulse-beat than during the period of rest, but an artery
which is very hard during the pulse-beat may be hard also during the pause

144 THE PULSE-CURVES OF VARIOUS ARTERIES.

between the pulse-beats, or it may be very soft, as in insufficiency of the aortic
valves. In this case, after the systole of the left ventricle, owing to the incom-
petency of the semi-lunar valves, a large amount of blood flows back into the
ventricle, so that the arteries are thereby suddenly rendered partially empty. [The
sudden collapse of the artery gives rise to the characteristic "pulse of unfilled
arteries. "]

Under similar conditions, the volume of the pulse is obvious from the size of
the sphygmogram, so that we speak of a large and a small pulse (P. magnus and
parvus). Sometimes the pulse is so thready and of such diminished volume that
it can scarcely be felt. A large pulse occurs in disease when, owing to hyper-
trophy of the left ventricle, a large amount of blood is forced into the aorta. A
small pulse occurs under the opposite condition, when a small amount of blood is
forced into the aorta, either from a diminution of the total amount of the blood,
or from the aortic orifice being narrowed, or from disease of the mitral valve ; again,
where the ventricle contracts feebly, the pulse becomes small and thready.
Sometimes the pulse differs on the two sides, or it may be absent on one side.

Waldenburg constructed a "pulse-clock " to register the tension, the diameter
of the artery, and the volume of the pulse upon a dial. It does not give a graphic
tracing, the results being marked by the position of an indicator.

72. The Pulse-Curves of Various Arteries.

1. Carotid (Fig. 54, A.; Fig. 58, 1, II, III ; Fig. 64, C and C,).

The ascending part is very steep the apex of the curve (Fig. 58, P)
is sharp and high. Below the apex there is a small notch the
"AORTIC NOTCH" (Fig. 58, K) which depends on a positive wave
formed in the root of the aorta, owing to the closure of the aortic
valves, and propagated with almost wholly undiminished energy
into the carotid artery. Quite close to this notch, if the curve be
obtained with minimal friction, the first elastic vibration occurs (Fig.
58, II, e). Above the middle of the descending part of the curve is the
dicrotic elevation, E, produced by the reflection of a positive wave
from the already closed semi-lunar valves. The dicrotic wave is rela-
tively small on account of the high tension in the carotid artery.
After this the curve falls rapidly, but in its lowest third two small
elevations may be seen. Of these the former is due to elastic vibration.
The latter represents a second dicrotic wave (Fig. 58, III, R), (Landois,
Moens). Here there is a true tricrotism, which is more easily obtained
from the carotid on account of the shortness of the arterial channel.

Moens describes the "aortic elevation" as occurring at the moment of the
closure of the aortic valves.

2. Axillary Artery (Fig. 58, IV).

In this curve the ascent is very steep, while in the descent near the
apex there is a small (aortic) elevation, K, caused by a positive wave,
produced by the closure of the aortic valves. Below the middle there

PULSE-CURVES OF VARIOUS ARTERIES. 145

is a tolerably high dicrotic elevation, R, higher than in the carotid
curve; because in the axillary artery the arterial tension is less, and
permits a greater development of the dicrotic wave. Further on, two
or three small elastic vibrations occur, e, e.

3. Radial Artery (Fig. 54, B; Fig. 58, V-X; Fig. 64, R and R,).

The line of ascent (Fig. 58) is tolerably high and sudden some-
what in the form of a long/. The apex, P, is well marked. Below
this, if the tension be high, two elastic vibrations may occur (V, e, e), but
if it be low, only one (VI to IX, e). About the middle of the curve is
the well-marked dicrotic elevation, R.

This wave is least pronounced in a small hard pulse, and when the
artery is much distended (Fig. 58, VII, Rj); it is larger when the
tension is low (Fig. 56, IX, R), and is greatest of all when the
pulse is dicrotic (X, R). Two or three small elastic elevations occur
in the lowest part of the curve.

4. Femoral Artery (Fig. 58, XI, XII).

The ascent is steep and high the apex of the curve is not unfre-
quently broad, and in it the closure of the aortic valves (K) is
indicated. The curve falls rapidly towards its lower third. The
dicrotic elevation, R, occurs late after the beginning of the curve, and
there are also small elastic elevations (e, e).

5. Pedal Artery (Fig. 58, XIV, XV), and Posterior Tibial
(Fig. 54, C, and Fig. 58, XIII).

In pulse-curves obtained from these arteries, there are well-marked
indications that the apparatus (heart) producing the waves is placed at

Fig. 61.

A, curve of posterior tibial, and B, pedal artery of a man. Curves written by the
angiograph upon a vibrating plate attached to a tuning-fork.

a considerable distance. The ascent is oblique and low the dicotric
elevation occurs late. Two elastic vibrations (Fig. 58, XIV, e, e) occur

10

1 vibration is
= 0-01613 sec.

146 ANACROTISM.

in the descent, but they occur very close to the apex, while the elastic
vibrations at the lower part of the curve are feebly marked. In
Fig. 61, A is from the posterior tibial, and B from the pedal artery
of the same individual. When measured, they give the following

result :

A B

12 . . .9-59

13 . . . 20 20

14 . . . 30-5 32

1-6 . . 61 62-5

73. Anacrotism.

As a general rule, the line of ascent of a pulse-curve has the form of an /, and is
nearly vertical. The arterial walls are thrown into elastic vibration by the pulse-
beat, and the number of vibrations depends greatly upon the tension of the arterial
walls.

The distension of the artery, or what is the same thing, the ascent of the sphyg-
mogram, usually occurs so rapidly that it is equal to one elastic vibration. The
elongated /-shape of the ascent is fundamentally just a prolonged elastic vibration.
When the number of vibrations causing the elastic variation is small, and when
the line of ascent is prolonged, two elevations occasionally occur in the line of
ascent. Such a condition may occur normally (Fig. 56, VIII at 1 and 2 ; X at 1
and 2). When a series of closely-placed elastic vibrations occur in the upper part
of the line of ascent, so that the apex appears dentate and forms an angle with the
line of ascent, then the condition becomes one of Anacrotism (Fig. 62, a, a),
which, when it becomes so marked, may be characterised as pathological (Landois).
Anacrotism of the pulse occurs when the time of the influx of the blood is longer
than the time occupied by an elastic vibration. Hence it takes place :

(1.) In dilatation and hypertrophy of the left ventricle, e.g., Fig. 62, A, a tracing
from the radial artery of a man suffering from contracted kidney. The large
volume of blood expelled with each systole requires a long time to dilate the tense
arteries.

(2.) When the extensibility of the arterial wall is diminished even the normal
amount of blood expelled from the heart at every systole requires a long time to
dilate the artery. This occurs in old people where the arteries tend to become
rigid, e.g., in atheroma. Cold also stimulates the arteries so that they become less
extensile. Within one hour after a tepid bath, the pulse assumes the anacrotic
form (Fig. 62, D) (G. v. Liebig.)

(3.) When the blood stagnates in consequence of great diminution in the velocity
of the blood-stream, as occurs in paralysed limbs, the volume of blood propelled
into the artery at every systole no longer produces the normal distension of the
arterial coats, and anacrotic notches occur (Fig. 62, B).

(4.) After ligature of an artery, when blood slowly reaches the peripheral part
of the vessel through a relatively small collateral circulation, it also occurs. If
the brachial artery be compressed so that blood slowly reaches the radial, the
radial pulse may become anacrotic. It often occurs in stenosis of the aorta, as the
blood has difficulty in getting into the aorta (Fig. 62, C).

Recurrent Pulse. If the radial artery be compressed at the wrist,
the pulse-beat reappears on the distal side of the point of pressure
through the arteries of the palm of the hand (Janaud, Neidert). The

ANACROTISM.

117

curve is anacrotic, and the dicrotic wave is diminished, while the elastic
elevations are increased.

I.

III.

Anacrotic pulse-curves A, B, C, D, from the radial artery ; a, a, the anacrotic
notches; I., II., III., curves with anacrotic elevations a in insufficiency of
the aortic valves.

(5.) A special form of anacrotisni occurs in cases of well-marked insufficiency of
the aortic valves. Practically, in these cases, the aorta remains permanently open.
The contraction of the left auricle causes in the blood a wave-motion, which is at
once propagated through the open mouth of the aorta into the large blood-vessels.
This wave is followed by the wave caused by the contraction of the hypertrophied
left ventricle, but of course the former wave is not so large as the latter. In
insufficiency of the aortic valves, the auricular wave occurs before the ventricular
wave in the ascending part of the curve. The auricular is well marked only in
the large vessels, for it soon becomes lost in the peripheral vessels. Fig. 62, I., was
obtained from the carotid of a man suffering from well-marked insufficiency of the
aortic valves, with considerable hypertrophy of the left ventricle and left auricle.
The ascent is steep, caused by the force of the contracted heart. In the apex of
the curve are two projections, A is the anacrotic auricular wave, and V is the
ventricular wave. Fig. 62, II. , is a curve obtained from the subclavian artery of
the same individual. In the femoral artery the auricular projection is only
obtained when the friction of the writing-style is reduced to the minimum, and
when it occurs it immediately precedes the beginning of the ascent (Fig. 62
III., a). The pulse-curve, in cases of aortic insufficiency, is also characterised
by (1) its considerable height; (2) the rapid fall of the lever from the apex of the
curve, because a large part of the blood which is forced into the aorta regurgitates

148 INFLUENCE OF RESPIRATORY MOVEMENTS ON PULSE-CURVE.

into the left ventricle when the venti'icle relaxes; (3) not unfrequently a pro-
jection occurs at the apex, due to the elastic vibration of the tense arterial wall ;
(4) the dicrotic wave (R) is small compared with the size of the curve itself,
because the pulse-wave, owing to the lesion of the aortic valves, has not a suffi-
ciently large surface to be reflected from. The great height of the curve is
explained by the large amount of blood projected into the aortic system by the
greatly hypertrophied and dilated ventricle.

74. Influence of the Respiratory Movements on

the Pulse-Curve.

The respiratory movements influence the pulse in two ways : (1)
in a purely physical way, by diminishing the arterial pressure during
each inspiration and increasing it during expiration; (2) the respir-
atory movements are accompanied by stimulation of the vasomotor
centre, which produces variation of the blood-pressure.

(a.) Normal Respiration. During inspiration, owing to the dilatation
of the thorax, more arterial blood is retained within the chest, while at
the same time, venous blood is sucked into the right auricle by
aspiration; as a consequence of this, the tension in the arteries during
inspiration must be less. The diminution of the chest during expiration
favours the flow in the arteries, while it retards the flow of the venous
blood in the venae cavse two factors which raise the tension in the
arterial system. The difference of pressure explains the difference in
the form of the pulse-curve obtained during inspiration and expiration,
as in Fig. 63 and Fig. 58, I., III., IV., in which J indicates the part of
the curve which occurred during inspiration, and E the expiratory por-
tion. The following are the points of difference: (1.) The greater dis-
tension of the arteries during expiration causes all the parts of the

Fig. 63.

Influence of the respiration upon the sphygmogram, after Riegel J, during in-
spiration; E, during expiration.

curve occurring during this phase to be higher; (2.) the line of
ascent is lengthened during expiration, because the expiratory thoracic
movement helps to increase the force of the expiratory wave; (3.)

VALSALVA'S AND MULLER'S EXPERIMENTS. 149

owing to the increase of the pressure the dicrotic wave must be less
during expiration; (4.) for the same reason the elastic elevations
are more distinct and occur higher in the curve near its apex. The
frequency of the pulse is slightly greater during expiration than during
inspiration.

(6.) This purely mechanical effect of the respiratory movements is
modified by the simultaneous stimulation of the vasomotor centre
which accompanies these movements. At the beginning of inspiration
the blood-pressure in the arteries is lowest, but it begins to rise during
inspiration, and increases until the end of the inspiratory act, reaching
its maximum at the beginning of expiration. During the remainder
of the expiration the blood-pressure falls until it reaches its lowest
level again at the beginning of inspiration (compare 85, /), the pulse-
curves are similarly modified, and exhibit the signs of greater or less
tension of the arteries corresponding to the phases of the respiratory
movements (Klemensiewicz, Knoll, Schreiber, Lbwit). [There is, as it
were, a displacement of the blood-pressure curve relative to the respira-
tory curve.]

Forced Respiration. With regard to the effect produced on the
pulse-curve by a powerful expiration and a foi'ced inspiration, observers
are by no means agreed.

Valsalva's Experiment. Strong expiratory pressure is best produced
by closing the mouth and nose, and then making a great expiratory
effort ; at first there is increase of the blood-pressure and the formation
of pulse-waves resembling those which occur in ordinary expiration,
the dicrotic wave being less developed ; but, when the forced pressure
is long continued, the pulse-curves have all the signs of diminished
tension (Riegel, Frank, and Sommerbrodt). This effect is due to the
action of the vasomotor centre, which is affected reflexly from the
pulmonary nerves. We must assume that forced expiration, such
as occurs in Valsalva's experiment, acts by depressing the activity of
the vasomotor centre (compare Vol. ii.) Coughing, singing, and declaim-
ing, act like Valsalva's experiment, while the frequency of the pulse
is increased at the same time (Sommerbrodt). After the cessation
of Valsalva's experiment, the blood-pressure rises above the normal state
(Sommerbrodt), almost as much as it fell below it; the normal con-
dition being restored within a few minutes (Lenzmann).

Muller's Experiment. When the thorax is in the expiratory phase,
close the mouth and nose, and take a deep inspiration so as forcibly to
expand the chest ( 60). At first the pulse-curves have the char-
acteristic signs of diminished tension, viz., a higher and more distinct
dicrotic wave; then the tension can, by nervous influences, be in-
creased, just as in Fig. 64, where C and R are tracings taken from the

150 INFLUENCE OF RESPIRATORY MOVEMENTS ON PULSE-CURVE.

carotid and radial arteries respectively, during Miiller's experiment,
in which the dicrotic waves, r, r, indicate the diminished tension in the
vessels. In Cj and E 19 taken from the same person during Valsalva's
experiment, the opposite condition occurs.

Fig. 64

C, curve from the carotid, and R, radial, during Miiller's experiment ; GX and Rj,
from the same vessels during Valsalva's experiment. Curves written on a
vibrating surface.

On expiring into a vessel resembling a spirometer (see Respiration), (Waldenburg's
respiration apparatus), and filled with compressed air, the same result is obtained as
in Valsalva's experiment the blood-pressure falls and the pulse-beats increase;
conversely, the inspiration from this apparatus of air under less pressure acts like
Miiller's experiment, i.e., it increases the effect of the inspiration, and afterwards
increases the blood-pressure, which may either remain increased on continuing the
experiment, or may fall (Lenzmann).

The inspiration of compressed air diminishes the mean blood-pressure (Zuntz),
and the after-effect continues for some time. The pulse is more frequent both
during and after the experiment. Expiration in rarified air increases the blood-
pressure (Zuntz, Lenzmann). The effects which depend upon the action of the
nervous system do not occur to the same extent in all cases. Exposure to com-
pressed air in a pneumatic cabinet lowers the pulse-curve, the elastic vibrations
become indistinct, and the dicrotic wave diminishes and may disappear (v.
Vivenot). The heart's beat is slowed and the blood-pressure raised (Bert,

Fig. 65.
Pulsus paratloxus, after Kussmaul E, expiration; J, inspiration.

Jacobsohn, Lazarus). Exposure to rarified air causes the opposite result, which is a
sign of diminished arterial tension.

INFLUENCE OP PRESSURE ON FORM OF PULSE-CURVE. 151

Pulsus FaradoXTlS. Under pathological conditions, especially when there is
union of the heart or its large vessels with the surrounding parts, the pulse dur-
ing inspiration may be extremely small and changed, or may even be absent. This
condition has been called pulsus paradoxus (Griesinger, Kussmaul).

It depends upon a diminution of the arterial lumen during the inspiratory move-
ment. Even in health, it is possible by a change of the inspiratory movement to
produce the p. paradoxus (Riegel, Sommerbrodt).

75, Influence of Pressure upon the Form of the

Pulse-Curve,

It is most important to know the actual pressure which is applied to an artery
while a sphygmogram is being taken. The changes affect the form of the curve as
well as the relation of the individual parts thereof. In Fig. 66, a, b, c, d, e, are
radial curves ; a was taken with minimal pressure, b with 100, c 200, d 250, and e
450 grammes pressure, while A, B, C, D, show the relations as to the time of
occurrence of the individual phenomena where the weight was successively
increased. The study of these curves yields the following results: (1) When the
weight is small, the dicrotic wave is relatively less ; the whole curve is high. (2)
With a moderate weight (100 - 200 grammes) the dicrotic wave is best marked, the
whole curve is somewhat lower. (3) On increasing the weight, the size of the

200

250

450

A 100

B 170

C 220 D

Fig. 66.
Various forms of curves (radial) obtained by gradually increasing the pressure.

A

B

C

J O

gi

6

5;

1-a,

10

1-3, .

.. 18

I?"

16,

1-4,

. 25

234

23;

1-5, .

. 34

32

32

1-b, .

41

1-6, .

. 44

464

45

152 RAPIDITY OF TRANSMISSION OF PULSE- WAVES.

dicrotic wave again diminishes. (4) The fine elastic vibrations preceding the
dicrotic wave appear first when a weight of 220 to 300 grammes is used. (5) The
rapidity of the pulse changes with increasing weight, the time occupied by the
ascent becoming shorter, the descent becoming longer. (6) The height of the entire
curve decreases as the weight increases. In every sphygmogram the pressure
under which it was obtained ought always to be stated.

In Fig. 66, A, B, C, D, are curves obtained from the radial artery of a healthy
student. The pressure exerted upon the artery for A was 100; B, 170; C, 220;
and D, 240 grms. The time occupied by the various events was :

D

1 vibration
= 0-01613

sec.

If pressure, be exerted upon an artery for a long time the strength of the pulse is
gradually increased. If, after subjecting an artery to considerable pressure, a
lighter weight be used, not unfrequeiitly the pulse-curve assumes the form of a
dicrotic pulse, owing to the greater development of the dicrotic elevation. When
strong pressure is applied, the blood is forced to find its way through collateral
channels. When the chief artery ceases to be compressed, the total area is, of
course, considerably and suddenly enlarged, which results in the pi'oduction of a
dicrotic elevation. Fig. 58, X, is such a dicrotic curve obtained after considerable
pressure had been applied to the artery.

76. Rapidity of Transmission of Pulse-Waves,

The pulse-wave proceeds throughout the arterial system from the
root of the aorta, so that the pulse- is felt sooner in parts lying near the
heart than in the peripheral arteries. E. H. Weber calculated the
rate of the pulse-wave as 9'240 metres [28^ feet] per sec. from the
difference in time between the pulse in the external maxillary artery
and the dorsal artery of the foot. Czermak showed that the elasticity
was not equal in all the arteries, so that the velocity of the pulse-wave
cannot be the same in all. The pulse-wave is propagated more slowly
in the arteries with soft extensile walls than in arteries with resistant
and thick walls, so that it is transmitted more rapidly in the arteries
of the lower extremities than in those of the upper. It is still slower
in children.

77. Propagation of the Pulse- Wave in Elastic

Tubes.

Waves similar to the pulse may be produced in elastic tubes. (1) According to
E. H. Weber the velocity of propagation of the waves is 11 '295 metres per sec.;

PROPAGATION OF PULSE-WAVES IN ELASTIC TUBES.

153

according to Bonders, 11-14 metres (34 - 43 feet). (2) According to E. H. Weber
increased internal tension causes only an inconsiderable decrease ; Rive found a
great decrease ; Donders found no obvious difference ; while Marey found an increased
velocity. (3) Donders found the velocity to be the same in tubes, 2 mm. in dia-
meter, as in wider tubes, but Marey believes that the velocity varies when the
diameter of the tube changes. (4) The velocity is less the smaller the elastic
coefficient. (5) The velocity increases with increased thickness of the wall, while
it diminishes when the specific gravity of the fluid increases.

Moens has recently formulated the following laws as to the velocity of propaga-
tion of waves inelastic tubes: (1) It is inversely proportional to the square root
of the specific gravity of the fluid. (2) It is as the square root of the thickness
of the wall, the lateral pressure being the same. (3) It is inversely as the square
root of the diameter of the tube, the lateral pressure being the same. (4) It is
as the square root of the elastic coefficient of the wall of the tube, the lateral
pressure being the same (Valentin).

Experiments With Caoutchouc Tubes. For this purpose Landois employs
the following apparatus (Fig. 67): A large tuning-fork, A (35 cmtr. long), carries
on one of its arms a glass-plate, P (25 cmtr. long, and 5 cmtr. broad), while the other
arm is weighted, G. The tuning-fork is fixed by an iron holder, T, to a movable
piece of wood which can be pushed along with the hand in a groove on a support
H, H. When the glass-plate is smoked, the curved needle of the angiograph
writes its movements upon it. The fork, when it vibrates, makes little teeth in
the curve, and the value of each vibration is estimated beforehand. Every com-
plete vibration in this instrument is equal to 0'01613 sec.

Velocity of the Waves in Elastic Tubes filled with Water or Mercury.

Take a soft extensible elastic tube, A, 8 '80 metres long, 1 mm. thick, and

Fig. 67.

Instrument for measuring the velocity of the pulse-wave in an elastic tube con-
taining water or mercury A, tuning-fork ; B, ampulla ; A, elastic tube ; P,
glass-plate smoked; Q, manometer; x, pad of lever of angiograph; writing-
style, D.

154 VELOCITY or THE PULSE-WAVE IN MAN.

7 mm. diameter. If 1 metre of the tube is weighted with 1 kilo, it elongates 68
cmtr. An ampulla, B, capable of containing 50 cmtr., is fixed to one end of the
tube, while to the other end of the ampulla is fixed a mercurial manometer, Q.

Fig. 67.

Pulse-curve from an elastic tube registered upon a plate attached to a vibrating

tuning-fork.

The tube, A, is shut close to the ampulla every time the pressure is mea-
sured, in order to obviate the occurrence of oscillation in the mercury. A certain
portion of the tube, say 8 metres, is measured. The beginning, a, and end, b,
of this stretch of tubing are placed under the pad, x , of the angiograph. When
a positive wave is produced by compressing the ampulla, the writing-lever is raised
twice, the first time when the wave passes the first part of the tube, o, under the
pad, and the second time when the end part of the tube, b, is distended by the
wave. The curve obtained is shown in Fig. 67, in which the two elevations,
1 and 2, are obvious. The time between the two may be ascertained by counting
the number of vibrations of the tuning-fork. The experiments gave the following
results :

(A.) The velocity of the wave is 11 '809 metres per sec.

(B.) The intra-vascular pressure has a decided influence on the velocity: thus,
in the tube, A, with 18 cmtr. (Hg.) pressure, the velocity per metre = 0'093 sec.,
while with 21 cmtr. pressure (Hg.) = 0'095 sec. per metre.

(C.) The specific gravity of the liquid influences the velocity of the pulse-wave.
In mercury the wave is propagated four times more slowly than in water (Marey
and Landois).

(D.) The velocity in a tube which is more rigid and not so extensile is greater
than in a tube which is easily distended.

78, Velocity of the Pulse-Wave in Man.

Landois obtained the following results in a student whose height was 174 centi-
metres : Difference between carotid and radial = 0*074 sec. (the distance being
taken as 62 centimetres); carotid and femoral = '068 sec.; femoral (inguinal
region) and posterior tibial = 0'097 sec. (distance estimated at 91 centimetres).

The velocity of the pulse-wave in the arteries of the upper extre-
mities=:9-43 metres per sec., and in those of the lower extremity 9'40
metres per second. The velocity is greater in the less extensible arteries

VELOCITY or 1 THE PULSE-WAVE IN MAN.

155

of the lower extremities than in those of the upper limb. For the same
reason it is less in the peripheral arteries and in the yielding arteries
of children (Czermak).

E. H. Weber estimated the velocity at 9 '24 metres per sec.; Garrocl, 9 -10 '8
metres; Grashey, 8' 5 metres; Moens, 8" 3 metres, and with diminished pressure
during Valsalva's experiment (p. 112) 7'3 metres.

In animals, haemorrhage (Haller), slowing of the heart produced by stimulation
of the vagus (Moens), section of the spinal cord, deep morphia-narcosis, and dilata-
tion of blood-vessels by heat, produce slowing of the velocity, while stimulation of
the spinal cord accelerates it (Grimm ach).

The wave-length of the pulse-wave is obtained by multiplying the
duration of the inflow of blood into the aorta=0'OS to 0'09 sees.
(p. 86) by the velocity of the pulse-wave.

Method. Place the knobs of two tambours (Fig. 52) upon the two arteries to
be investigated, or place one over the apex-beat and the other upon an artery.
These receiving tambours are connected with two registering tambours, as in
Brondgeest's pansphygmograph ( 67, Fig. 52) so that their writing-levers are
directly over each other, and so arranged as to write simultaneously on one vibrating-
plate attached to a tuning-fork. [Or they may be made to write upon a revolving
cylinder, whose rate of movement is ascertained by causing a tuning-fork of a
known rate of vibration to write under them.] In Fig. 68, H is the curve obtained
from the heart, and C from the radial artery. The apparatus is improved by using
rigid tubes and filling them with water, in which all impulses are rapidly communi-
cated. In arteries which are distant from each other, or in the case of the heart
and an artery, the two knobs of the receiving tambours may be connected by means
of a Y-tube with one writing-lever. In Fig. 68, B is a curve from the radial artery
taken in this way. In it v H P indicates contraction of the ventricle ; H, the
apex of the ventricular contraction ; P, the primary apex of the radial curve ; v, the

H

m

B

Fig. 68.

A, curve of radial artery on a vibrating surface (1 vib. =0'01613 sec.) ; P, apex
of curve ; e, e, elastic vibrations ; B,, dicrotic wave ; B, curve of same radial
taken along with the heart-beat ; v, H, P, contraction of the ventricle ; H,
curve of the heart-beat ; C, of the radial artery, taken simultaneously. The
arrows indicate the identical points in both curves. In B, v to p = 9 vibrations.

156

FURTHER PULSATILE PHENOMENA.

beginning of the ventricular contraction ; p, of the radial pulse. A is the curve of
the radial artery alone. From these curves, as well as from H and C, it is evident
that in this instance 9 vibrations occur between the beginning of the ventricular
contraction (in H at 22) until the beginning of the pulse in the radial artery (in C
at 13), so that 0' 15 sec. elapses between these two events (1 vibration = 0*01613 sec.).
In Fig. 69 the difference between the carotid and the posterior tibial pulse =
0-137 sec.

/^^^^^

"* ^ww^/

Caret.

Fig. 69.

Curves of the carotid and posterior tibial taken simultaneously with Broudgeest's
pansphygmograph writing upon a vibrating plate, attached to a tuning-fork.
The arrows indicate the identical moment of time in each curve.

Pathological. In cases of diminished extensibility of the arteries, e.g., in
atheroma (p. 127), the pulse-wave is propagated more rapidly. Local dilatations of
the arteries, as in aneurisms, cause a retardation of the wave, and a similar result
arises from local constrictions. Relaxation of the walls of the vessels in high
fever retards the movement (Hamernjk).

79. Further Pulsatile Phenomena.

1. In the mouth and nose, when they are filled with air, and the glottis
closed, pulsatile phenomena (due to the arteries in their soft parts), may be found
communicating a movement to the contained air. The curves obtained are
relatively small, and closely resemble the curve of the carotid. A similar pulse
is obtained in the tympanum with intact membrana tympani, and when the
soft parts of the tympanum are congested (Schwartze, Trb'ltsch).

2. Entoptical Pulse, After violent exercise, an illumination corresponding to
each pulse-beat, occurs on a dark optical field. When the optical field is bright,
an analogous darkening occurs (Landois). The ophthalmoscope occasionally reveals
pulsation of the retinal arteries (Jiiger), which becomes marked in insufficiency of
the aortic valves (Quincke, 0. Becker, Helfreich).

3. Pulsatile Muscular Contraction. The orbicularis palpebrarum muscle
contracts under similar conditions synchronously with the pulse ; and it is perhaps
due to the pulse-beat exciting the sensory nerves reflexly. The brothers Weber
found that not unfrequently while walking, the step and pulse gradually and in-
voluntarily coincide.

4. When the legs are crossed as one sits in a chair, the leg which is supported
is raised with each pulse-beat, and it gives also a second or dicrotic elevation.

5. If, while a person is quite quiet, the incisor teeth of the lower jaw be made
just to touch the upper incisors very lightly, we detect a double beat of the lower

VIBRATIONS COMMUNICATED TO THE BODY BY THE HEART. 157

against the upper teeth, owing to the pulse-beat in the external maxillary artery
raising the lower jaw. The second elevation is clue to the closure of the semi- lunar
valves, and not to a dicrotic wave.

6. Brain and Fontanelles. The large arteries at the base of the brain com-
municate a movement to it, while similar movements occur with respiration rising
during expiration and falling during inspiration. These movements are visible
in the fontanelles of infants. The respiratory movements depend upon variations in
the amount of blood in the veins of the cranial cavity, and also upon the respiratory
variations of the blood -pressure.

7. Amongst pathological phenomena, are the beating in the epigastrium, as in
hypertrophy of the right or left ventricle, caused, it may be, by deep insertion of
the diaphragm, and it may be partly by the beating of a dilated abdominal aorta or
coeliac axis.

Abnormal dilatations (aneurisms) of the arteries cause an abnormal pulsation,
while theyproducea slowing inthe velocity of the pulse-wave in the corresponding artery.
Hence the pulse appears later in such an artery than in the artery on the healthy
side. Hypertrophy and dilatation of the left ventricle cause the arteries near the
heart to pulsate strongly. In the analogous condition of the right ventricle, the beat
of the pulmonary artery may be seen and felt in the second left intercostal space.

80. Vibrations communicated to the Body by the

action of the Heart,

The beating of the heart and large arteries communicates vibrations to the body
as a whole, but the vibration is not simple but compound.

Gordon was the first to represent this pulsatory vibration graphically. If a

B

/LL

K

"1

n

Fig. 70.

II, Elastic support for registering the molar motions of the body K, a wooden
box ; B, feet of patient ; p, cardiograph ; a, b, elastic tubing. I, III Vibra-
tion curves of a healthy person. IV Similar curve obtained from a patient
suffering from insufficiency of the aortic valves and great hypertrophy of the
heart.

158 VIBRATIONS COMMUNICATED TO THE BODY BY THE HEART.

person be placed in an erect attitude in the scale of a large balance, the index
oscillates, and its movements coincide with the heart's movements.

Fig. 70, I, shows a curve obtained by Gordon, written directly by the index of
the spring balance. The lowest part of the curve corresponds to the systole of the
ventricle.

Landois employed the following arrangement : Take a long four-sided box, K,
open at the top, and arrange several coils, a, b, of stout caoutchouc tubing round
one end. A wooden board, B, smaller than the opening in the box, is so placed
that it rests with one end on the caoutchouc tubing, and with the other on the
narrow end of the box. The person to be experimented upon, A, stands vertically
and firmly on this board. A receiving tambour, p, is placed against the surface
of the board next the elastic tube, which registers the vibrations of the foot
support. Fig. Ill is a curve showing such vibrations, each heart-beat being followed
in this case by four oscillations. It corresponds to I. To ascertain the relations
and causes of these vibrations, it is necessary to obtain, simultaneously, a tracing
of the heart and the vibratory curve. For this purpose use the two tambours of
Brondgeest's pansphygmograph (p. 71), placing one nob or pad over the heart,
and the other on the foot-support, and allow the writing-tambours to inscribe their
vibrations on a glass-plate attached to a tuning-fork.

In the lower or cardiac impulse curve, Fig. 71, the rapidly-rising part is due to
the ventricular systole. It contains S vibrations (1 vib. =0'01G13 sec.). The
beginning of the ventricular systole is indicated in the fig. by - 36 - 3 - 17.

If the corresponding numbers in the upper or vibratory curve are studied, it is
obvious that at the moment of ventricular systole the body males a downward vibration,
i.e., it exercises greater pressure upon the foot - support. Gordon interprets his
curve as giving exactly the opposite result. This downward motion, however,
lasted only during 5 vibrations of the tuning-fork : during the last 3 vibrations,
corresponding to the systole, there is an ascent of the body corresponding to a less
pressure upon the foot-plate. When the ventricle empties itself, it imdergoes a
movement in a downward and outward direction Gutbroclt's "reaction impulse."

Fig. 71.

The upper curve is the vibration-curve of a healthy person, and the lower one a

tracing of the apex beat.

In the upper curve analogous numbers are employed to indicate the vibrations
occurring simultaneously, viz., -28- 11 -10. The closure of the semi-lunar

THE BLOOD-CURRENT. 159

valves is well marked in the three heart-beats at 20-20. This closure is
indicated in analogous points in both curves, after which there is a descent of the
foot-support, and this corresponds to the downward propagation of the pulse-wave
through the aorta to the vessels of the feet.

In insufficiency of the aortic valves, as shown in Fig. 70, IV, the vibration com-
municated to the body is very considerable.

81. The Blood- Current.

The closed and much-branched vascular system, whose walls are
endowed with elasticity and contractility, is not only completely
filled with blood but it is over-filled. The total volume of the blood is
somewhat greater than the capacity of the entire vascular system.
Hence it follows that the mass of blood must exert pressure on the
walls of the entire system, thus causing a corresponding dilatation of
the elastic vascular walls (Brunner). This occurs only during life;
after death the muscles of the vessels relax, and fluid passes into the
tissues, so that the blood-vessels come to contain less fluid and some
of the vessels may be emptied.

If the blood were uniformly distributed throughout the vascular
system and under the same pressure, it would remain in a position of
equilibrium (as after death). If, however, the pressure be raised in
one section of the tube the blood will move from the part where the
pressure is higher to where it is lower ; so that the blood-current is a
result of the difference of pressure within the vascular system. If either
the aorta or the venae cavse be suddenly ligatured in a living animal,
the blood continues to flow, gradually more slowly, until the difference
of pressure is equalised throughout the entire vascular system.

The velocity of the current will be greater the greater the difference
of pressure, and the less the resistance opposed to the blood-stream.

The difference of pressure which causes the current is produced by the
heart (E. H. Weber). Both in the systemic and pulmonary circulations
the point of highest pressure is in the root or beginning of the arterial
system, while the point of lowest pressure is in the terminal portion of
the venous orifices at the heart. Hence, the blood flows continually
from the arteries through the capillaries into the venous trunks.

The heart keeps up the difference of pressure required to produce
this result ; with each systole of the ventricles a certain quantity of
blood is forced into the beginning of the arteries, while at the same
time an equal amount flows from the venous orifices into the auricles
during their diastole (E. H. Weber).

Bonders added another important fact viz., that the action of the
heart not only causes the difference of pressure necessary to establish a
blood-current, but that it also raises the mean pressure within the vascular

160 THE BLOOD-CURRENT.

system. The terminations of the veins at the heart are wider and
more extensible than the arteries where they arise from the heart.
As the heart propels a volume of blood into the arteries equal to that
which it receives from the veins, it follows that the arterial pressure
must rise more rapidly than the venous pressure diminishes, since the
arteries are not so wide nor so extensible as the veins. Thus the total
pressure must also increase.

The volume of blood expelled from the ventricles at every systole
would give rise to a jerky or intermittent movement of the blood
stream 1. if the tubes had rigid walls, as in such tubes any pressure
exerted upon their contents is propagated momentarily throughout the
length of the tube, and the motion of the fluid ceases when the pro-
pelling force ceases. 2. The flow would also be intermittent in
character in elastic tubes if the time between two successive systoles
were longer than the duration of the current necessary for the compen-
sation of the difference of pressure caused by the systole. If the time
between two successive systoles be shorter than the time necessary to
equilibrate the pressure, the current will become continuous, provided
the resistance at the periphery of the tube be sufficiently great to bring
the elasticity of the tube into action. The more rapidly systole follows
systole, the greater becomes the difference of pressure, and the more
distended the elastic walls. Although the current thus produced is con-
tinuous, a sudden rise of pressure is caused by the forcing in of a mass
of blood at every systole, so that with every systole there is a sudden
jerk and acceleration of the blood-stream corresponding to the pulse
(compare 64).

This sudden jerk-like acceleration of the blood-current is propagated
throughout the arterial system with the velocity of the pulse-wave :
both phenomena are due to the same fundamental cause. Every
pulse-beat causes a temporary rapid progressive acceleration of the
particles of the fluid. But just as the form-movement of the pulse is
not a simple movement, neither is the pulsatile acceleration a simple-
acceleration. It follows the course of the development of the pulse-
wave. The pulse-curve is the graphic representation of the pulsatory
acceleration of the blood-stream. Every rise in the curve corresponds
to an acceleration, every depression to a retardation of the current.

Method. These facts are capable of demonstration by means of very simple
physical experiments. [Tie a Higginson's syringe to a piece of an ordinary gas-
pipe. On forcing water through the tube by compressing the elastic pump, the
water will flow out at the other end of the tube in jets, while during the intervals
of pulsation no water will flow out. As the walls of the tube are rigid, just as
much fluid flows out as is forced into the tube. If a similar arrangement be made,
and a long elastic tube be used, a continuous outflow is obtained, provided the
pulsations occur with sufficient rapidity and the length of the tube, or the resist-

CURRENT IN THE CAPILLARIES. 161

ance at its periphery, be sufficient to bring the elasticity of the tube into action.
This can be done by putting a narrow cannula in the outflow end of the tube, or
by placing a clamp on it so as to diminish the exit aperture. This apparatus
converts the intermittent flow into a continuous current.] The fire-engine is a
good example of the conversion of an intermittent inflow into a uniform outflow. The
air in the reservoir is in a state of elastic tension, and it represents the elasticity
of the vascular walls. When the pump is worked slowly, the outflow of the water
occurs in jets, and is interrupted. If the pumping movement be sufficiently rapid,
the compressed air in the reservoir causes a continuous outflow, which is distinctly
accelerated at every movement of the pump.

Current in the Capillaries. In the capillary rebels the pulsatile
acceleration of the current ceases with the extinction of the pulse-
wave, The great resistance which is offered to the current towards
the capillary area causes both to disappear. It is only when the
capillaries are greatly dilated, and when the arterial blood-pressure
is high, that the pulse is propagated through the capillaries into the
beginning of the veins. A pulse is observed in the veins of the sub-
maxillary gland after stimulation of the chorda tympani nerve, which
contains the vascular or vaso-dilator nerves for the blood-vessels of
this gland. If the finger be constricted with an elastic band so as to
hinder the return of the venous blood, and to increase the arterial
blood-pressure, while at the same time dilating the capillaries, an inter-
mittent increased redness occurs, which corresponds with the well-
known throbbing sensation in the swollen finger. This is due to the
capillary pulse. [Koy and Graham Brown found that pulsatile pheno-
mena were produced in the capillaries, by increasing the extra-vascular
pressure (p. 173). Quincke called attention to the capillary pulse which
can often be seen under the finger nails. Extend the fingers completely,
when a whitish area appears under the nails. A red area near the free
margin of the nail advances and retires with each pulse-beat. It is
well-marked in some diseased conditions of the heart, and is probably
produced by increased extra-vascular pressure,]

82. Schemata of the Circulation.

E. H. Weber constructed a scheme of the circulation. It consisted of a force-
pump with properly arranged valves to represent the heart, portions of gut for
the arteries and veins, and a piece of glass tubing containing a piece of sponge to
represent the capillaries. Various schemes have been invented, including the very
complicated one of Marey [and the thoroughly practical one of Rutherford].

83. Capacity of the Ventricles.

Since the right and left ventricles contract simultaneously, and
just the same volume of blood passes through the pulmonary as

11

IB 2 ESTIMATION OF THE BLOOD-PRESSURE.

through the systemic circulation, it follows that the right ventricle must
be just as capacious as the left. The capacity of the ventricles has
been estimated in the following ways :

(1.) Directly, by filling the dead ventricle with blood (Santorini, 1724; Legallois
and Collin). This method is unsatisfactory and inaccurate. (2.) All the vessels of
the relaxed heart are ligatured, the heart excised, and the contents of the cavities
estimated (Abegg, 1848). (3.) Volkmann estimated the capacity to be -^ of the
body- weight i.e., for a man of 75 kilos. = 187 '5 grms.

84. Estimation of the Blood-Pressure.

(A.) In Animals : Method Of Hales, The Rev. Stephen Hales (1727) was
the first to introduce a long glass tube into a blood-vessel in order to estimate the
blood-pressure by measuring the height of the column of blood, i.e., how high the
blood rose in the tube. The tube was provided at its lower end with a copper
tube bent at a right angle (Pitot's tube). [The tube he used was one-sixth of an
inch bore and about nine feet long, and was inserted into the femoral artery of a
horse. The height to which the blood rose in the tube was noted, as well as the
oscillations that occurred with every pulsation. From the height of the column
of fluid he calculated the force of the heart.]

(2.) The Hsemadynamometer of Poiseuille, This observer (1828) used a

U-shaped tube partially filled with mercury a manometer which was brought into
connection with a blood-vessel by means of a rigid tube. [The mercury oscillated
with every pulsation, and the extent of the oscillations was read off by means of a
scale attached to the bent tube. He called the instrument a hamadynamometer].

[(3. ) Vierordt used a tube five or six feet long, and filled it with a solution of
sodium carbonate, thus preventing much blood from entering the tube, while
at the same time the soda solution prevented the coagulation of the blood.]

(4.) C. Ludwig's Kymograph. C. Ludwig employed a U-shaped mano-
meter of the same kind, but he placed a light float (Fig. 72, d, s) upon
the surface of the mercury in the open limb of the tube. A
writing-style, /, placed transversely on the free-end of the float,
inscribed the movements of the float and, therefore, of the mercury
upon a cylinder, c, caused to revolve at a uniform rate. This
apparatus registered the height of the blood-pressure, as well as
the pulsatile and other oscillations occurring in the mercury. Volk-
mann called this instrument a kymograph or " wave-writer." The
difference of the height of the column of mercury, c, d, in both limbs
of the tube indicates the pressure within the vessel. If the height of
the column of mercury be multiplied by 13'5, this gives the height
of the corresponding column of blood. Setschenow placed a stop-cock
in the lower bend, h, of the tube. If this be closed so as just to
permit a small aperture of communication to remain, the pulsatile
vibrations no longer appear, and the apparatus indicates the mean
pressure. By the term mean pressure is meant the limit of pressure,
above and below which the oscillations occurring in an ordinary blood-

LUDWIG'S KYMOGRAPH.

163

pressure tracing range. [Briefly, it is the average elevation of the
mercurial column.]

Fig. 72.
I, Scheme of C. Ludwig's kymograph ; II, Fick's spring-kymograph.

In a blood-pressure tracing, such as Fig. 74, each of the smaller waves corre-
sponds to a heart-beat, the ascent corresponding to the systole and the descent to the
diastole. The large undulations are due to the respiratory movements. It is clear
that the heart-beat is expressed as a simple rise and fall (Fig. 74), so that the curve
of the heart-beat obtained with a mercurial kymograph differs from a sphygmo-
graphic curve. A perfect recording instrument ought to indicate the height of the
blood-pressure and also the size, form, and duration of any wave-motion com-
municated to it. The mercurial manometer does not give the true form of the
pulse-wave, as the mercury, when once set in motion, executes vibrations of its
own, owing to its great inertia, and thus the finer movements of the pulse-wave are
lost. Hence a mercurial kymograph is used for registering the blood-pressure, and
not for obtaining the exact form of the pulse- wave. Instruments with less inertia
and with no vibrations peculiar to themselves, are required for this purpose. [The
theory of the mercurial manometer has been carefully worked out by Mach and
also by v. Kries.]

[Method. Expose the carotid of a chloralised rabbit, and isolate a portion of
the vessel between two ligatures, or two spring clamps. With a pair of scissors
make an oblique slit into the artery, and into it insert a straight glass cannula,
directing the open end of the cannula towards the heart. Fill the cannula
with a saturated solution of sodium carbonate, taking care that no air-bubbles
enter, and connect it with the lead tube which goes to the descending limb
of the manometer. The tube which connects the artery with the manometer must
be flexible and yet inelastic, and a lead tube is best. It is usual to connect a
pressure-bottle, containing a saturated solution of sodium carbonate, by means of an
elastic tube, with the tube attached to the manometer. This bottle can be raised
or lowered. Before beginning the experiment, raise the pressure-bottle until there
is a positive pressure of several inches of mercury in the manometer, or until the
pressure is about equal to the estimated blood-pressure, and then clamp the tube

164

SPRING -KYMOGRAPH.

V

of the pressure-bottle where it joins the lead tube. By having this positive
pressure, the escape of blood from the artery into the solution of sodium carbonate
is to a large extent avoided. When all is ready, the ligature on the cardiac side

of the cannula is removed, and
immediately the float begins to
oscillate and inscribe its move-
ments upon the recording sur-
face. The fluid within the
artery exerts pressure laterally
upon the sodium carbonate
solution, and this in turn trans-
mits it to the mercury.]

[When we have occasion to
take a tracing for any length
of time, it must be written
upon a strip of paper which
is moved at a uniform rate
in front of the writing-
style on the float (Fig. 73).
Various arrangements are em-
ployed for this purpose, but it
is usual to cause a cylinder to
revolve so as to unfold a roll or
riband of paper placed on a
movable bobbin. As the cylin-
der revolves, it gradually winds
off the strip of paper, which is
kept applied to the revolving
surface by ivory friction wheels.
In Fick's complicated kymo-
graph a, long strip of smoked
paper is used. The writing-
style may consist of a sable
brush, or a fine glass pen filled
with aniline blue dissolved in
water, to which a little alcohol
and glycerine are added.]

[In order to measure the
height of the pressure, we
must know the position of the

Fig. 73.

Ludwig's improved form of revolving cylinder, S,
which is moved by the clock-work in the box,
A, and regulated by a Foucault's regulator
placed on the top of the box. The
disc, D, moved by the clock-work, presses
upon the two wheels, ??, which can be raised
or lowered by the screw, L, thus altering the
position of n on D, so as to cause the
cylinder to rotate at different rates. The
cylinder itself can be raised by the handle, v.
On the left side of the figure is a mercurial
manometer. When the cylinder is used, it is
covered with smoked smooth paper.

abscissa or line of no pressure, and it may be recorded at the same time as the
blood-pressure or afterwards. ]

[In Fig. 74, - x is the zero-line or the abscissa, and the height of the vertical
lines or ordinates may be measured by the millimetre scale on the left of the
figure. The height of the blood -pressure is obtained by drawing ordinates from
the curve to the abscissa, measuring their length, and multiplying by two.]

(5.) Spring-Kymograph. A. Fick (1864) constructed a " spring-kymo-
graph" on the principle of Bourdon's manometer (Fig. 72, II).

A hollow C-shaped metallic spring, F, is filled with alcohol. One end of the
hollow spring is closed, and t he other end, covered by a membrane, is brought into
connection with a blood-vessel by a junction-piece filled with a solution of sodium
carbonate. As soon as the communication with the artery is opened, the pressure
rises, and the spring, of course, tends to straighten itself. To the closed end, b,

ESTIMATION OF THE BLOOD-PRESSURE IN MAN.

165

there is fixed a vertical rod attached to a series of levers, /<, i, k, e, one of which
writes its movements upon a surface moving at a uniform rate. The blood-pressure
and the periodic variations of the pulse are both recorded, although the latter ia
not done with absolute accuracy.

Fig. 74.

Blood-pressure curve of the carotid of a dog obtained with a mercurial manometer.
- x = line of no pressure, zero line, or abscissa ; y-y' is the blood-pressure
tracing with small waves, each one caused by a heart-beat, and the large
waves due to the respiration. A millimetre scale shows the height of the
pressure in millimetres of mercury.

[Bering improved Pick's instrument (Fig. 75). a, b, c, is the hollow spring filled
with alcohol, and communicating at a with the lead tube, d, passing to the cannula
in the artery. To c is attached a series of light wooden levers with a writing-
style, s. The lower part of 4 dips into a vessel, e, filled with oil or glycerine which
serves to damp the vibrations of the levers. At f is a syringe communicating
with the tube, d, filled with solution of sodic carbonate, and used for regulating
the amount of fluid in the tube connecting the manometer with the blood-vessel.
The whole apparatus can be raised or lowered on the toothed rod, h, by means of
the millhead opposite, y, to which all the parts of the apparatus are attached.]

(B.) In Man the blood-pressure may be estimated by means of a
properly graduated sphygmoyraph (p. 130). The pressure required to
abolish the movement of the lever indicates approximately the vascular
tension. Landois (Schobel) investigated the radial pulse in a healthy
student, and obtained a mean blood-pressure equal to 550 grammes.

(2.) By a manometric method v. Basch estimated the blood-prea-

166

BLOOD-PRESSURE IN THE ARTERIES.

sure. He placed a capsule containing fluid upon a pulsating artery, and
the capsule communicated with a mercurial manometer. As soon as
the pressure within the manometer slightly exceeded that within the

artery, the artery was
compressed so that a
sphygmograph placed
on a peripheral por-
tion of the vessel
ceased to beat. Both
arrangements, how-
ever, do not give the
exact pressure within
the artery, they only
indicate the pressure
which is required to
compress the artery
and the overlying soft
parts. The pressure
required to compress
the arterial walls, how-
ever, is very small
compared with the
blood-pressure. It is

Fig. 75.
Fick's Spring-manometer, as improved by Hering.

only 4 mm. Hg. v. Basch estimated the pressure in the radial artery
of a healthy man to be 135 - 165 millimetres of mercury.

In children the blood-pressure increases with age, height, and weight. In the
superficial temporal artery from 2-3 years, it is 97 mm. ; from 12-13 years, 113
mm. Hg. (A. Eckert, c. 100). The blood-pressure is raised immediately after
bodily movements ; it is higher when a person is in the horizontal position than
when sitting, and in sitting than in standing (Friedmann). After a cold as well
as after a warm bath (L. Lehrnann), the first effect is an increase of blood-
pressure and of the quantity of urine (Grefberg).

85. Blood-Pressure in the Arteries.

The following results have been obtained by experiment on systemic
arteries:

(a.) Mean Blood-Pressure. The blood-pressure is very considerable,
varying within pretty wide limits; in the large arteries of large
mammals, and perhaps in man it is = 140 - 160 millimetres (5*4 to 6 -4
inches) of a mercurial column.

The following results have been obtained, those marked thus * by Poiseuille,
and those + by Volkmann -.

BLOOD-PRESSURE IN THE ARTERIES. 167

* Carotid, Horse, 161 mm.
+ , ,, 122-214 mm.

,, Dog, 151 mm.

130- 190 mm. (Ludwig).

+ ,, Goat, 118-135 mm.

+ Aorta of frog, 22-29 mm.

+ Gill artery of Pike, 35-84 mm.

Brachial artery of man during an

operation, 110-120 mm. (Faivre).

Perhaps too low owing to the

injury.

+ ,, Rabbit, 90 mm.
+ Fowl, 88-171 mm.

The pressure in the aorta of mammals varies from 200 to 250 mm. Hg.

As a general rule, the blood-pressure in large animals is higher than
in small animals, because in the former the blood-channel is consider-
ably longer, and there is greater resistance to be overcome. In very
young and in very old animals the pressure is lower than in individuals
in the prime of life.

(b.) Branching of the Blood-Vessels. Within the large arteries the
blood-pressure diminishes relatively little as we pass towards the
periphery, because the difference of the resistance in the different
sections of large tubes is very small. As soon, however, as the
arteries begin to divide frequently, and undergo a considerable diminu-
tion in their lumen, the blood-pressure in them rapidly diminishes,
because the propelling energy of the blood is much weakened owing
to the resistance which it has to overcome (p. 118).

(c.) Amount of Blood. The blood-pressure is increased with greater
fitting of the arteries, and vice versd ; it

Increases

1. With increased and accelerated

action of the heart;

2. In plethoric persons;

3. After increase of the quantity of

blood by direct transfusion, or
after a copious meal.

Decreases

1. During diminished and enfeebled

action of the heart;

2. In anaemic persons;

3. After haemorrhage or considerable ex-

cretions from the blood by sweat-
ing, the urine, severe diarrhoea.

The blood-pressure does not vary in the same proportion as the variations in the
amount of blood. The vascular system, in virtue of its muscular tissue, has the
property, within liberally wide limits, of accommodating itself to larger or smaller
quantities of blood (C. Ludwig and Worm Miiller, 102, d). Small and moderate
haemorrhages (in the dog to 2 '8 per cent of the body- weight) have no obvious effect
on the blood-pressure. After a slight loss of blood the pressure may even rise (Worm
Miiller). If a large amount of blood be withdrawn, it causes a great fall of the
blood-pressure (Hales, Magendie), and when haemorrhage occurs to 4-6 per cent.
of the body-weight, the blood-pressure = 0. The transfusion of a moderate amount
of blood does not raise the mean arterial blood-pressure. [There are important
practical deductions from these experiments, viz., that the blood-pressure cannot
be diminished directly by moderate blood-letting, and that the blood-pressure is
not necessarily high in plethoric persons.]

Capacity of the Vessels. The arterial pressure rises when the
capacity of the arterial system is diminished, and conversely. The
plain circularly-disposed muscular fibres of the arteries are the chief

1G8

BLOOD-PRESSURE IN THE ARTERIES.

agents concerned in this process. When they relax, the arterial blood-
pressure falls, and when they contract, it rises. These actions of
muscular fibres are controlled and regulated by the action of the vaso-
motor nerves (vol. ii.)

(e.) Collateral Vessels. The arterial pressure within a given area of
the vascular system must rise or fall according as the neighbouring
areas are diminished, whether by the application of pressure, or a
ligature, or are rendered impervious, or as these areas dilate.
The application of cold or warmth to limited areas of the body
increasing or diminishing the atmospheric pressure on a part the
paralysis or stimulation of certain vaso-motor areas (vol. ii.), all pro-
duce remarkable variations in the blood-pressure. [The effect of
dilatation of a large vascular area on the arterial pressure is well
shown by what happens when the blood-vessels of the abdomen are
dilated. If the central end of the superior cardiac nerve of a rabbit be
stimulated, after a few seconds the blood-vessels of the abdomen dilate,
and gradually there is a steady fall of the blood-pressure in the
systemic arteries. Fig. 76 is a blood-pressure tracing showing the
height of the blood-pressure before stimulation, a. The stimulation
was continued from a to b, and after a certain latent period, there is
a steady fall of the blood-pressure. The nerve which causes this reflex

Fig. 76.

Kyniographic tracing showing the effect on the blood-pressure of stimulation of the central end of the
depressor nerve in the rabbit. Stimulation began at , and ended at b ; ox, the abscissa.

RESPIRATORY UNDULATIONS IN THE BLOOD-PRESSURE CURVE. 169

dilatation of the abdominal blood-vessels, and consequent lowering of
the blood-pressure, is also called the depressor nerve.

(/.) Respiratory Undulations. The arterial pressure also undergoes
regular variations or undulations owing to the respiratory movements.
These undulations are called respiratory undulations (Figs. 74 and
77). Stated broadly, during every strong inspiration the pressure
rises, and during expiration it falls ( 74). This is not quite correct
(see below). These undulations may be explained by the fact, that
with every expiration, the blood in the aorta is subjected to an increase
of pressure through the compressed air in the chest ; with every
inspiration, on the other hand, it is diminished owing to the diminu-
tion of the air in the lungs acting upon the aorta. Besides, the
inspiratory movements of the chest aspirate blood from the venae
cavse towards the heart, while expiration retards it, and thus influences
the blood-pressure. The undulations are most marked in the arteries
lying nearest to the heart. The respiratory undulations are due in part
to a stimulation or condition of excitement of the vaso-motor centre,
Avhich runs parallel with the respiratory movements. This stimulation
of the vaso-motor centre causes the arteries to contract, and thus the
blood-pressure is raised. The variations in the pressure which depend
upon a varying activity of the vaso-motor centre are known as the
curves of Traube and Hering (p. 171). In Fig. 77 are represented a
blood-pressure tracing and a curve of the movements of respiration
(thick line) taken simultaneously in a dog by C. Ludwig and Einbrodt.
The blood-pressure tracing was obtained from the carotid artery, while

Fig. 77.

Kyinographic blood-pressure tracing (upper, thin line), and respiration curve
(lower, thick line), taken simultaneously ex, expiration ; in, inspiration ; c, c,
heart-beats. The large curves in the blood-pressure tracing are due to
respiration (Ludwig and Einbrodt).

the pressure within the thorax was measured by means of a manometer
placed in connection with one pleural cavity. In this curve, when
expiration begins (at ex), and as the expiratory-pressure rises, the blood-
pressure rises, while when inspiration begins (at in) both fall. The
blood-curve, however, begins to rise (at c) before expiration com-

170 RESPIRATORY UNDULATIONS IN THE BLOOD-PRESSURE CURVE.

mences i.e., during the last part of the act of inspiration. This
is due to the contraction of the arteries, caused by impulses sent
from the vaso-motor centre. It is also aided by the circum-
stance that during inspiration there is an increased inflow of
venous blood to the heart, so that when it contracts, more blood is
forced into the arteries. [The maxima and minima of the two curves
do not coincide exactly, but in addition the number of pulse-beats is
greater in the ascent than in the descent. This is well-marked
in a blood-pressure tracing from a dog's carotid, while in a
rabbit this difference of the pulse-rate is but slightly marked. The
smaller number of pulse-beats during the descent i.e., during the
greater part of expiration is due to the activity of the cardio-
inhibitory c