78 ALBERT C. CRAWFORD 



iodin, but nftt the iron reaction. However, he was inclined to believe that 

 both reactions were probably due to the same chromogen, although he did 

 not isolate it. As it was soluble in alcohol, he concluded that it was not 

 a protein. 



These color reactions of Vulpian were confirmed by Harley(a.) and by 

 Virchow(o-). The latter believed that the chromogen was confined to the 

 intercellular substance and did not occur in the medullary cells. 



During the period between the appearance of Vulpian' s report and 

 that of Oliver and Schaefer the propulsive ideas in the study of the chem- 

 istry of the suprarenal glands became the isolation and identification of 

 the chromogenic substance, or its color products, and of the toxic com- 

 pounds ; although some attention was directed to other constituents, inosit 

 and large amounts of potassium were proved to be present (Marino-Zuco, 

 Kulz). Cloez and Vulpian stated that the suprarenal glands contained 

 alkaline phosphates and sodium chlorid and thought that taurocholic and 

 hippuric acids were present in these organs, and that the first would break 

 down into choloidic acid and taurin. After treatment with HC1, Seligsohn 

 obtained crystals which he believed to be taurin. He stated that the glands 

 contained Ca, Fe, Mg and benzoie acid. However, the work of Stadel- 

 mann(a) showed that the suprarenal glands did not contain hippuric, ben- 

 zoic or the biliary acids (Beier). 



A number of workers, Holm, Arnold (&), Krukenberg, Brunner, under- 

 took to isolate the chromogen, or its derivatives. 



Holm macerated suprarenal glands with alcohol and, after filtering, 

 evaporated the alcohol, then precipitated the residue with a solution of 

 neutral lead acetate. The filtrate was precipitated with lead subacetate, 

 then with copper acetate and finally heated. The heavy metals were re- 

 moved from the filtrate by H 2 S. On concentrating, a violet-colored sub- 

 stance separated. This substance went into solution with acids. Holm 

 pointed out that, on adding ammonia to an acid extract of the glands, the 

 pigment separated in violet flakes ; hence it was a base, but he did not have 

 enough material for further study. He said that these organs con- 

 tained a chromogen which, on oxidation, passed into a coloring matter. 



Krukenberg inferred that the compound which gave the iron re- 

 action was different from the one which reddened on oxidation. He based 

 this partly on Vulpian's experiments with the suprarenal glands of the 

 python and partly on his own observation that after long boiling in an 

 open vessel, aqueous extracts of the suprarenals gradually lost their 

 capacity to react with ferric salts. He believed that the red pigment 

 was not always the same, because after obtaining the maximal red color 

 with iodin, silver still gave another color (purple). 



Krukenberg repeated Arnold's method, i. e., the suprarenals were 

 digested with alcohol on the water bath, then ammonia and neutral lead 

 acetate were added to the filtrate. The lead precipitate was extracted 



