HYPOXANTHIN. 369 



Sundwik (p. 337) will require confirmation. Nevertheless, the re- 

 searches of Fischer have shown that at least indirectly the purin 

 bases may be converted into uric acid and vice versa (p. 337). 



Hypoxanthin was once regarded as a step lower than guanin 

 in the series of nitrogenous products of regressive metamorphosis, 

 and consequently was considered as derived from guanin. The 

 investigations of Kossel, however, show that it arises not from 

 guanin but from adenin. On the other hand, guanin is to be looked 

 upon as the source of xanthin. It is probable that in the organism 

 it is oxidized as soon as it is set free from the nuclein, forming suc- 

 cessively xanthin, uric acid, urea, etc., and the small quantity pres- 

 ent in the urine is all that has escaped oxidation. The fact that 

 hypoxanthin is so widely distributed in the organism, and in much 

 larger quantities than was formerly supposed, shows that it may con- 

 stitute, together with the closely related bodies creatin, xanthin, 

 guanin, etc., a part of the antecedents of urea and of uric acid. 

 This view is furthermore strengthened since hypoxanthin is espe- 

 cially abundant in those organs which are most active in producing 

 metabolic changes in the body, viz., the liver and spleen. The fact 

 that tryptic ferments apparently decompose hypoxanthin and xanthin 

 has been already pointed out (p. 348). The conversion of hypo- 

 xanthin into uric acid by an emulsion of liver cells has been shown 

 by Wiener (p. 343). 



When fed to dogs, it was observed that the amount of hypoxan- 

 thin present in the urine decreased, and even became less in amount 

 than before the experiment ; but, on the other hand, the amount of 

 xanthin and especially of uric acid in the urine was found to have in- 

 creased above the normal. This shows that hypoxanthin in the body 

 is oxidized probably first to xanthin, then into uric acid. According 

 to Robert, hypoxanthin is a true muscle stimulant (see p. 345). 



Hypoxanthin is a white, colorless, crystalline powder, sometimes 

 in part amorphous ; according to Bruhns, pure hypoxanthin does 

 not form floccules and bunches of microscopic needles, but usually 

 coherent crusts, which consist of roundish, sharp-cornered granules ; 

 some resemble octahedra. The synthetic hypoxanthin separates 

 from hot aqueous solution as a colorless crystalline powder (Fischer). 

 It is soluble in about 300 parts of cold water (Strecker), but accord- 

 ing to Fischer the synthetic base is soluble at 19° in 1415 and at 

 23° in 1370 parts of water. This agrees fairly with Scherer's result 

 1 : 1090. The base separates slowly from aqueous solutions, and 

 when pure the solubility, even in the beginning, is less than 1 :300. 

 At the end of four days Bruhns found it to be 1 : 1880. It is more 

 easily soluble in boiling water (78 parts Strecker, 69.5 parts Fischer), 

 and, on cooling, separates in the form of white, crystalline floccules, 

 thus diflfering from xanthin which is amorphous. According to 

 Scherer the solubility in warm water is 1 to 180. The solubility in 

 24 



