RESPIRATION xiii 



oxygenation of the blood in the tissues helps the blood to combine with CO 2 and 

 thus partly prevents the pressure of COz from rising, 90. CC>2 may be given off 

 in the lungs although the CO2 pressure is lower in the venous blood than in the 

 alveolar air, 91. Approximate mathematical treatment of the dissociation curve 

 for CO2, 92. Effect of the CO2 in blood on the dissociation of oxyhaemoglobin 

 in the systemic blood, 94. The physiological buffers which prevent abrupt rise 

 or fall of CO2 pressure in the respiratory center, 96. Effects on the alveolar 

 CO2 pressure of holding the breath or forced breathing, 96. Abruptness of 

 rises or falls of oxygen pressure in the respiratory center, 100. This abrupt- 

 ness is the cause of periodic breathing when the alveolar oxygen pressure is low, 

 103. Artificial production of periodic breathing in healthy persons, 103. 

 Why shortage of oxygen and consequent periodic breathing do not occur nor- 

 mally, 104. Addendum, Discussion of some recent theories of the carriage of 

 CO2 by blood, 105. Interchange of acid between plasma and corpuscles, 106. 



CHAPTER VI. THE EFFECTS OF WANT OF OXYGEN 108 



Immediate dependence of the body for its oxygen supply on air, 108. Anox- 

 aemia produced by lowered pressure of oxygen in the air, 109. Effects on the 

 breathing, 109. These effects largely transitory, 109. Lowering of the thresh- 

 old of alveolar CO2 pressure, but alveolar CO2 pressure still regulates the 

 breathing, no. Variability of the effects in different individuals, in. 

 Death from anoxaemia caused by excessive removal of CO2 from the blood, 112. 

 Excess of COa in the air counteracts the effects of deficiency of oxygen, 112. 

 Mere increase of breathing does not diminish the anoxaemia, though it dimin- 

 ishes the cyanosis, 114. The peculiar symptoms produced by forced breathing 

 are apparently due mainly to anoxaemia, 115. Subsidiary effects of CO2 in re- 

 lieving anoxaemia, 117. Periodic breathing at high altitudes is caused by 

 anoxaemia, 117. Effects of anoxaemia on the frequency of breathing, 118. 

 Effects in causing fatigue of the breathing, 121. Effects of anoxaemia on the 

 circulation, 121. Increase in pulse rate is largely transitory, 123. Cyanosis 

 and anoxaemia not the same thing, 125. Effects on the nervous system, 125. 

 Insidious character of these effects, 125. Effects on muscular power, senses, 

 memory, and powers of judgment, 126. Personal experiences, 128. Moun- 

 tain sickness and conditions of its production, 128. Nervous after symptoms 

 following severe anoxaemia, 129. After effects on heart, 129. After effects 

 on respiratory center, 130. Adaptation to want of oxygen, 130. 



CHAPTER VII. THE CAUSES OF ANOXAEMIA . .132 



Defective saturation of arterial haemoglobin, 132. One cause of this is 

 defective distribution of air in the lungs, 133. Experimental proof and ex- 

 planation of this, 133. Effects of holding the breath, and explanation of the 

 anoxaemia produced, 141. Cause of difference between clinical Cheyne-Stokes 

 breathing and periodic breathing produced artificially in healthy persons, 141. 

 Significance of rapid breathing in cases of illness, 142. Danger of sudden 

 attacks of restricted and rapid breathing, 143. Causes of anoxaemia in em- 

 physema, bronchitis, and asthma, 145. Orthopnoea and its causes, 146. A 

 second cause of arterial anoxaemia is defective pressure of oxygen in the in- 

 spired air, 146. Immediate effects and after effects, 147. The percentage 

 saturation of the arterial haemoglobin is lower than corresponds to the oxygen 



