SIGNIFICANCE OF THE SUPRARENAL GLANDS 133 



300,000 to 1 :9,000,000. The limits of concentration have not the same sig- 

 nificance as the limits of output. For it has been shown (/) (1917) that in 

 one and the same animal during an experiment the concentration varies 

 inversely as the rate of blood flow through the suprarenals within the limits 

 of error of the method of assay employed. In other words, while the output 

 remains constant the concentration of epinephrin in the suprarenal vein 

 blood may undergo great variations. Another way of stating the same 

 thing is that under our experimental conditions the epinephrin is given 

 off by the suprarenals at a steady rate, which is independent of changes 

 in the blood flow, just as carbon dioxid is given off by resting muscles at 

 a steady rate, which is not influenced by variations in the rate of blood 

 flow. Trendelenburg's(fr) statement (1911), that when the blood-pressure 

 (in cats) is reduced by hemorrhage and the minute outflow of blood from 

 the suprarenals correspondingly diminished the epinephrin concentra- 

 tion increases so much as to compensate for the- decreased flow, is in agree- 

 ment with the results of Stewart and Rogoff, although the number of his 

 observations was small and some of them were made by a method which 

 seems open to serious error, the estimation of the epinephrin concentra- 

 tion by the rise of pressure produced by injection of a given quantity of 

 cat's serum into guinea pigs. His rough estimate of the output of epineph- 

 rin at something like 0.0003 mgm. per minute per animal is also of the 

 same order of magnitude, although no doubt smaller if meant as an aver- 

 age. Ehrmann's statement (6) (1905) that the amount of epinephrin given 

 off in the cat is much less than in the rabbit is quite inaccurate. In so 

 far as it is not based upon technical errors it means only. that the concen- 

 tration was greater in the rabbit, which is likely enough as the blood- 

 pressure was probably lower and the blood flow, therefore, smaller. This 

 writer habitually confuses concentration with rate of output. O'Connor's 

 incidental statement, in an otherwise excellent paper, that in the rabbit 

 the output seems to diminish as the blood flow diminishes is probably 

 erroneous, unless, indeed, it applies to a condition of shock, more easily 

 induced in the rabbit than in the dog or cat, so profound and so prolonged 

 that the central nervous mechanism on which the secretion depends has 

 suffered materially. His estimate of the output at 0.0007 to 0.00014 mgm. 

 per minute per rabbit agrees sufficiently with the results of Trendelenburg 

 on the same animal (0.00015 to 0.0002 mgm. per kgm. per minute) and 

 with the few observations made on the rabbit by Stewart and Rogoff. 



In 17 dogs anesthetized with morphin and ether or with ether alone, 

 the concentrations of epinephrin in the suprarenal vein blood, assayed 

 on rabbit's intestine segments, were found to vary between 1 : 1,800, 000 and 

 1:18,000,000. The average output per kgm. of bodyweight per minute 

 was 0.00022 mgm. (Stewart and Rogoff (e)) (1917). Assuming that the 

 "adrenalin" solution employed by Hoskins and McClure(fr) contained 70 

 per cent of base, their average for 5 dogs estimated by the same method 



