124 THE ADRENALS AND THE RESPIRATORY BLOOD-CHANGES. 



And, although Bohr's experiments have been severely criti- 

 cised, it does not seem improbable in itself that the physical 

 process of diffusion is aided by some other process which may 

 provisionally be termed secretion." "As to the oxygen, we are 

 in the same position. Its partial pressure does not appear to 

 be always higher, even under normal conditions, in the alveoli 

 than in the arterial blood as it leaves the lungs. Indeed, Bohr 

 found that, in the majority of his observations on dogs, the 

 oxygen-tension was distinctly greater in the blood than in the 

 pulmonary air. And Haldane and Smith, using a new method, 

 have obtained a value for the oxygen-tension in human blood 

 (26.2 per cent, equal to 200 millimeters of mercury) that even 

 exceeds the partial pressure of oxygen in the external air and 

 is about twice as great as that of the air of the alveoli. . . . 

 Additional evidence in favor of the view that there is, besides 

 diffusion, an element of selective secretion in the interchange 

 of gases through the pulmonary membrane is afforded by a 

 study of the gases of the swim-bladder of fishes." 



Besides all the data recorded in this chapter, generally rec- 

 ognized facts i.e., facts generally known before this work was 

 written when submitted to a process of logical reasoning, also 

 lead to the conclusion that an intimate relationship exists 

 between the respiratory function and the suprarenal glands. 

 That a physiological relation between these organs and the 

 blood exists, is shown by the fact that, while characteristic 

 "bronzing" pigment is a derivative of haemoglobin, Addison's 

 disease is known to be due to disease of the suprarenal glands. 

 A "derivative" implicates the element of subdivision. Since, 

 therefore, the "bronze" pigment is a derivative, the supra- 

 renal glands must be concerned with the dissociation of the 

 blood-pigment from which the "bronze pigment" is derived. 

 This we know to be haemoglobin; the suprarenal glands must, 

 therefore, be connected with the dissociation of hemoglobin. 

 Again, since it is a lesion of the suprarenal glands that under- 

 lies this process, the glands must serve to keep the constituents 

 of hemoglobin together. To chemically disintegrate hemo- 

 globin we use reducing agents which act mainly by deoxidizing 

 this body. Hence, the suprarenal glands must furnish a sub- 

 stance which supplies oxygen to the hemoglobin constituents. 



