CHEMISTRY OF THE LEUCOM AINES. 301 



vital process, and the same chemical change may take place 

 in the animal organs. The same change very probably 

 takes place in the auto-digestion of yeast. Its formation 

 under these conditions can be represented thus : 



C,H,N, + H,0 = C,H,¥,0 + NH3. 



Hypoxanthine can be readily obtained from a number of 

 closely related substances. Thus, carnine, by the action of 

 oxidizing agents, is converted into hypoxanthine (page 328). 

 For this reason Weidel and Schutzenbergee regard 

 hypoxanthine as derived from carnine, but this view is now 

 entirely set aside by our present knowledge of the relation 

 of this base to nuclein. 



Again, it can be obtained from adenine (page 289) by the 

 action of nitrous acid. The relation that hypoxanthine 

 bears to uric acid is shown by the fact that the latter is 

 converted by nast^nt hydrogen first into xanthine, and 

 finjpUy into hypoxanthine. 



C,H,N,03 + 2H, = C,H,N,0 + 2H,0. 



Uaio Acid. 



This transformation of uric acid into hypoxanthine is of 

 especial importance, since together with Horbaczbwski's 

 synthesis of uric acid, accomplished by acting on urea with 

 either glycocoll or trichlorlactamide, it constitutes the last 

 step in the complete synthesis of hypoxauthine from its 

 elements. 



Hypoxanthine has been hitherto regarded as a step lower 

 than guanine in the series of nitrogenous products of 

 regressive metamorphosis, and consequently was considered 

 as derived from guanine. The investigations of Kossel, 

 however, show that it arises not firom guanine but from 

 adenine. On the other hand, guanine is to be looked upon 

 as the source of xanthine. It is probable that in the 

 organism it is oxidized as soon as it is set free from the 

 nuclein, forming successively xanthine, uric acid, urea, etc., 

 and the small quantity present in the urine is all that has 

 escaped oxidation. When fed to dogs, it was observed that 

 the amount of hypoxanthine present in the urine decreased, 



14 



