THE ADRENAL SECRETION AND PULMONARY RESPIRATION. 127 



tions themselves. Both in extravasated blood and in blood 

 taken from a case of carbonic-acid poisoning the haemoglobin 

 must be in more or less loose combination: i.e., more or less 

 deprived of its complement of suprarenal secretion. The fact 

 that so marked an affinity as that witnessed in venous blood 

 in the experiment referred to still exists shows how active 

 must be that exhibited by the blood of the organism when 

 possessed of its full physiological attributes. 



When we come to Bohr's experimental findings, which 

 tend to show that "carbon dioxide does not pass through the 

 walls of the alveoli by diffusion," they simply sustain what the 

 presence of an agency capable of endowing the blood with a 

 powerful affinity for oxygen at the seat of respiratory inter- 

 changes, the walls of the alveoli, would suggest, namely: 

 the conclusion that gaseous diffusion and endosmosis are un- 

 important factors in the pulmonary respiratory process, if they 

 take any part whatever in the phenomena of which it consists. 



Bohr's statement that the pressure of the oxygen in the 

 alveoli did not always appear higher, even under normal con- 

 ditions, than in the arterial blood, and that in dogs he had 

 found the oxygen-tension in the blood distinctly higher in the 

 majority of his experiments than in the pulmonary air, and 

 Haldane and Smith's observation, that in the human blood the 

 oxygen-tension was about twice as great as that of the alveolar 

 air, are likewise sustained. The hemoglobin, owing to its 

 powerful affinity for oxygen, takes it up from its surroundings 

 regardless of the variations of pressure, and, unless the oxygen 

 is proportionately replaced, it will entirely (Muller) exhaust 

 the element containing it. The relative tension of oxygen in 

 the blood and in the alveolar air is not, therefore, a ruling factor 

 in the process of physiological respiration; and the higher oxygen- 

 tension in the blood referred to, though subject to constant 

 perturbations, physiological and pathological, seems but a nor- 

 mal consequence of the presence in that blood of so potent an 

 agency for the absorption of oxygen as that represented by the 

 suprarenal secretion. 



If the views outlined in this chapter are based on solid 

 premises, the process of pulmonary respiration is approximately 

 as follows: 



