xii RESPIRATION 



showing the non-existence of "vagus apnoea," 47. — Afferent vagus excitations 

 coordinate the phases of breathing, 48. — The depth and vigor of breathing de- 

 pend on the chemical stimuli to the respiratory center,/^?g:=^Effects of resistance 

 on the rhythm of breathing, 50. — Artificial respiration-atid the vagus coordina- 

 tion of breathing, ,^0 .-^Normal breathing and afferent nervous control, 53. — 

 Evidence that the activity of the respiratory center depends on locally acting 

 chemical stimuli in the medulla oblongata, 53. — Physiological significance of 

 this fact, 54. — Fatigue of the respiratory center, 56. — The breathing in "sol- 

 dier's heart" and allied conditions, 52£;7'-"Neurasthenia" and fatigue, 56. — 

 Variations in individual susceptibility to fatigue of breathing, 57. 



CHAPTER IV. The Blood as a Carrier of Oxygen. 59 



General chemical properties of haemoglobin and oxyhaemoglobin, 59. — Meth- 

 aemoglobin and its properties, 59. — Action of ferricyanide in liberating oxygen 

 or CO from combination with haemoglobin, 60. — Oxyhaemoglobin and CO 

 haemoglobin are molecular compounds, 61. — The ferricyanide method of de- 

 termining the oxygen capacity of haemoglobin, 61. — The oxygen capacity of 

 haemoglobin is exactly proportional to its coloring power, 61. — The Gowers- 

 Haldane haemoglobinometer, 62. — Normal variations in haemoglobin percentage 

 of blood, 63. — Haemochromogen and its modifications, 64. — Relation between 

 oxygen capacity and iron of haemoglobin, 64. — Relation of haemochromogen 

 to haemoglobin, 66. — Ferricyanide method for ordinary blood-gas determina- 

 tions, 66. — Amount of available oxygen, in human arterial blood, 67. — Funda- 

 mental importance of the partial pressure of oxygen in the blood, 67. — "Partial 

 pressures," "vapor pressures," "diffusion pressures," and "concentrations" of 

 substances in the living body, 67. — Investigations of the laws of dissociation 

 of oxyhaemoglobin in blood, 68. — Work of Paul Bert, Hiifner, Loewy and 

 Zuntz, Bohr, Barcroft, 70. — Effects of salts, CO2, and acids or alkalies, 72. — 

 Physiological importance of the shape of the oxyhaemoglobin dissociation curve, 

 72. — Properties and dissociation curves of CO haemoglobin, 72. — Nature of 

 alterations produced by CO2 on the dissociation curves of CO haemoglobin and 

 oxyhaemoglobin, 76. — Relative affinities of oxygen and CO for haemoglobin, 

 74- — Evidence of differences in the chemical structure of haemoglobin in differ- 

 ent individuals and species, 77. — Use of haemoglobin for estimating partial 

 pressures of CO or oxygen, 79. — Explanation of the peculiarities of the dissocia- 

 tion curve of oxyhaemoglobin in blood, 80. — Equations for the dissociation 

 curves, 82. 



CHAPTER V. The Blood as a Carrier of Carbon 



Dioxide 84 



Amount of CO2 in normal human and dog's arterial blood, 84. — Amounts in 

 simple solution and chemical combination, 85. — The CO2 is combined with 

 alkali as bicarbonate, 84. — Why the bicarbonate dissociates appreciably with a 

 small fall in the partial pressure of CO2 in the blood, 85. — Haemoglobin and 

 other proteins act as acids in the living body, and do not combine with CO2, 

 though they play a most essential part in its carriage, 88. — The dissociation 

 curve for CO2 of human blood, 89. — Constancy of this curve for the same indi- 

 vidual, and relative constancy in different normal individuals, 89. — Evidence 

 that oxygen has a chemical action in liberating COj in the lungs, 92. — The de- 



