THE OXIDIZING SUBSTANCE OF THE BLOOD-PLASMA. 131 



worth considering. Still, we have seen how marked is the 

 affinity of the suprarenal secretion for this gas and mechanical 

 means might prove quite inadequate to dissociate them when 

 united. Again, the secretion is first poured into the vena 

 cava and there dissolved in the serum of its venous blood. 

 Thoroughly mixed with the latter when passed through the 

 heart, owing to the conformation of the cardiac valves, the 

 musculaB tendinese, etc., it must find in the serum a normal 

 vehicle at least during its presence in the prepulmonary vas- 

 cular channels. Does the serum beyond the lung still contain 

 suprarenal secretion? We have seen that such is not the case. 

 Indeed, its remarkable affinity for oxygen would hardly permit 

 it to pass through these organs and be exposed to the air 

 therein without its becoming oxidized, or at least converted 

 into some combination in which both the secretion and the 

 gas would lose their individual identities. 



We must not overlook the fact, however, that this com- 

 bination, to satisfy the needs of our inquiry, would have to 

 assume active functions. Again, the secretion and its extra- 

 pulmonary oxygen-laden successor would have to be antag- 

 onistic to fulfill physiological needs. In other words, before 

 reaching the lungs the secretion would possess a marked affinity 

 for oxygen, while the extrapulmonary compound would show 

 a correspondingly marked tendency to part with its oxygen 

 when bodies endowed with greater affinity for this element 

 would be brought into contact with it. 



Have we any ground for the belief that such an oxidizing 

 compound exists in the blood? An analytical study of this 

 question is necessarily a somewhat arduous one, but, fortu- 

 nately, direct evidence is not lacking: evidence that combines 

 the advantages of absolute reliability and at the same time 

 covers the field with sufficient fullness to warrant judicious 

 deductions. The paper to which we refer is that of Salkowski, 

 already quoted, and which includes, besides his own researches, 

 the results of those of Schmiedeberg, Jaquet, and Abelous and 

 Biarnes. 



In order to trace the connection between the observations 

 of these investigators and our views in respect to the part 

 played by the secretion of the adrenals in the process, it is 



9 



