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Scientific Proceedings (83). 



minute could not have been as much as 0.0000009 mgm. per 

 minute, for one adrenal. The segments used for the tests in these 

 experiments were extremely sensitive, and the limits of adrenalin 

 concentrations which could be detected with certainty were care- 

 fully determined. The eye reactions were negative. In these 

 two cats the rate of liberation of epinephrin, if any liberation 

 whatever was going on, must have been several hundred times 

 less than the rate in normal animals under the same experimental 

 conditions. 



It is scarcely necessary to point out that experiments yielding 

 completely negative results indicating the absence of epinephrin 

 with very sensitive test objects are much more important for the 

 questions studied than experiments in which small amounts of 

 epinephrin can still be detected. For it is impossible to be certain 

 that when a little epinephrin is found some of the fibers concerned 

 in the liberation may not have escaped section. 



3. Since these animals had completely recovered from the 

 operation and behaved in every way like normal animals, it must 

 be concluded that the liberation of epinephrin from the adrenals 

 is not indispensable for life or health, unless indeed the necessary 

 quantity is, even in the adrenal vein blood, below the limits of 

 detection by the methods used. It must be remembered that 

 the epinephrin in the adrenal blood is diluted enormously (prob- 

 ably at least 100 times) in the right heart; so that in these cats 

 the concentration in the arterial blood could not at most have 

 reached I : 40 billions and 1 : 70 billions, respectively. 



If the liberation of epinephrin is abolished by division in the 

 dorsal cord of the path concerned in it, as our experiments on 

 "Relation of the Spinal Cord to the Spontaneous Liberation of 

 Epinephrin" indicate, this corroborates the conclusion that 

 epinephrin is not indispensable. Numerous animals and men 

 have long survived such lesions. 



4. These experiments indicate that the entire liberation of 

 epinephrin from the adrenals is controlled by nerves. 



5. In a third cat (8 days after operation) the adrenal vein 

 blood contained epinephrin but in concentration not exceeding 

 1 : 125,000,000. The output of epinephrin per minute was prob- 

 ably not more at most than one-hundredth of what might be 

 expected in a normal animal. 



