THE ADRENAL BODIES 185 



Notwithstanding the almost universal acceptance of the 

 view that the action of adrenin is identical and co-terminous 

 with that of sympathetic nervous action, it is well to bear in 

 mind that the evidence is in some directions contradictory and 

 in others rather meagre. As will be seen from the table it is 

 by no means easy to formulate an absolute parallelism in every 

 instance, and the difficulty becomes still greater if we take into 

 consideration the different effects of varying doses of adrenin. 

 The parallel problem as to the effects of varying degrees of 

 stimulation upon the sympathetic fibres does not seem to have 

 been worked out. 



M. The Chemical Nature of the Active Substance of 

 the Adrenal Medulla and other Chromaphil Tissues 



It is one of the greatest triumphs of physiological chemistry 

 that within seven years of the discovery of the powerful effects 

 of extracts of the adrenal medulla, the active principle was 

 obtained in crystalline form, and that five years later its 

 composition has been so completely ascertained that it has 

 been synthesized, and the pure active synthetic product can 

 now be obtained from the manufacturing chemists. 



In 1856 Vulpian described a powerfully reducing substance 

 in the medulla of the adrenal body. This material was found 

 to give various colour reactions on being oxidized e.g., with 

 ferric chloride it gave a dark green or blue colour, and with 

 chlorine, bromine, or iodine water or caustic alkalies a rose red. 

 Several authors attempted, but without success, to isolate the 

 " chromogen " of the gland from a lead precipitate. They all 

 obtained decomposition products. Krukenberg, however, 

 established the important fact that the adrenal chromogen, in 

 regard to certain properties (iron reaction, reducing power, 

 production of a dark coloration with oxidizing agents), corre- 

 sponds with pyrocatechin. 



Immediately after the publication of the discovery of the 

 pressor action of adrenal extracts, Moore concluded that the 

 active substance is identical with the chromogen described by 

 Vulpian. 



Frankel, by treatment of adrenal extracts with alcohol, 

 acetone, and ether, obtained a syrupy preparation of great 

 physiological activity. This was the first claimant to the 



