64 THE PHYSIOLOGY OF THE ADRENALS. 



characterized this secretion as "colloid." Biedl 124 subsequently 

 found these masses to consist of clear, yellow, bright granules, 

 resembling blood-plaques or fragments of red blood-cells, 

 though the ratio of white and red corpuscles in the vessels was 

 normal. 



The earliest chemical investigations in this connection 

 were probably those of Vulpian, 126 of Paris, who found that 

 the juice expressed from the suprarenal glands of various ani- 

 mals contained a powerful reducing substance which gave 

 color-reactions obtainable with no other tissue of the organism. 

 Thus, with ferric chloride, this suprarenal juice gave an 

 emerald-green color, and with iodine solutions, a rose-carmine 

 tint. Attempts to isolate the chromogenic substances were 

 made by several investigators, including Virchow, Arnold, and 

 Holm, but without success. Krukenberg 126 many years later 

 concluded that the suprarenal chromogen was a non-volatile, 

 nitrogenous, and ferruginous organic acid, the green color- 

 giving substance being "more likely pyrocatechin accompany- 

 ing the chromogen." An alcoholic extract prepared by Brun- 

 ner 127 gave nearly all the pyrocatechin reactions, while the 

 addition of an alkali caused it to assume a brown color. Miihl- 

 mann 128 ascribed the blood-pressure-raising power to a pyro- 

 catechin derivative . taken up with ether from the residue of 

 fresh adrenals boiled with dilute hydrochloric acid, and which 

 became brown on exposure to light or contact with alkaline 

 solutions. The principal substance entering into its formation, 

 mainly derived from vegetable foodstuffs, were, he thought, 

 present in the blood and supposedly built up in the cortex. 

 Eecent investigations, however, have not sustained Miihlmann's 

 views. Giirber 129 not only found it impossible to establish the 

 relationship thought by Miihlmann to exist between the active 

 principle and pyrocatechin, but the latter substance did not, 



124 Biedl: Pflliger's Archiv, vol. Ixvii, H. 9 and 10, 1897. 



128 Vulpian: Comptes-Rendus, vol. xliii, pp. 663-665. Quoted by J. J. Abel and 

 A. C. Crawford, Johns Hopkins Hosp. Bull., July, 1897. 



128 Krukenberg: Virchow's Archiv, ci, 542-591, 1885. Quoted by Abel and 

 Crawford, loc. cit. 



127 Brunner: Schweizer Wochenschrift fur Pharmacie, xxx, 121-123. 



128 Muhlmann: Deutsche med. Wochenschrift, June 25, 1896. 



129 Giirber: Sitzungs. d. physik. med. Gesellschaft Wurzburg, 1897. 



