180 W. B. CANNON 



Another experiment of similar import performed by Cannon and 

 Rapport was that of extirpating the suprarenals and severing the hepatic 

 nerves without lowering blood pressure and without interfering with 

 vascular reflexes. Then a constant stream of epinephrin at the rate de- 

 clared by Stewart and Kogoff to be "normal" was introduced into the 

 femoral vein. While this flow was continuing uniformly, the brachial 

 nerve was stimulated. The blood pressure rose as usual, but there was 

 no increase in the rate of the denervated heart or at most an increase of two 

 beats per minute. "Redistribution of blood" was thus again proved inade- 

 quate as an explanation of the faster rate. 



5. According to Stewart and Rogoff (w) the denervated heart "has no 

 significance as an indicator of augmented epinephrin output" (1920). 

 Cannon and Rapport found, however, that in a "reduced" animal re- 

 peated equal doses of epinephrin, injected intravenously at a uniform rate, 

 repeatedly produced in a given animal the same or nearly the same maxi- 

 mal increases of heart beat, and further, that if the injections differed in 

 rate the increases likewise differed in degree. When the circulation is 

 simplified, as in the reduced anima], the cardiac acceleration is chiefly or 

 wholly dependent on the rate of injection, and is little, if at all, influenced 

 by variations in blood pressure. By matching epinephrin injections with 

 reflex adrenal secretion, it was shown that when the denervated heart 

 in the reduced animal is accelerated between 30 and 42 beats per minute, 

 the output from the suprarenal glands lies between 0.0032 and 0.0037 mg. 

 epinephrin per kilo per minute, i. e., more than ten times the amount 

 (0.00025 mg.) regarded by Stewart and Rogoff as the unvarying normal 

 secretion. 



The foregoing considerations reveal evidence which requires further 

 "explaining," if the conclusion is to be drawn that secretion of the 

 suprarenal glands is constant and unvarying. 



Discussion of the Methods Yielding Negative Evidence 



Since Stewart and Rogoff are alone in their view that there is no 

 marked change in the rate of secretion from the adrenal glands, it is per- 

 haps reasonable to inquire whether the peculiar method which they em- 

 ployed, rather than the various methods used by others, may not have 

 features which would account for the discrepant results. 



The method of fitewart and Rogoff. Stewart and Rogoff (&) obtained 

 evidence of adrenal secretion by the use of a "pocket" in the inferior vena 

 cava (1916). This pocket was made by clamping the vena cava immedi- 

 ately above the iliacs, then clamping the renal veins, emptying the cava 

 segment by stripping it upwards, and placing a clamp on the vessel above 

 the entrance of the lumbo-suprarenal veins. Any small branches of 



