CHEMISTRY OF THE LEUCOM A I NES. 301 



vital process, and the same chemical change may take place 

 in the animal organs. The same change very probably 

 pla<v in the auto-digestion of yeast. Its formation 

 these conditions can be represented thus : 



C 5 H 5 X 5 + H a O = C 6 H 4 N 4 + NH S . 



Bypoxanthine 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 SCHUTZENBERGER regard 

 hypoxanthiue 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 nascent hydrogen first into xanthine, and 

 finally into hypoxanthine. 



C 6 H 4 N 4 S + 2H 2 = C 6 H 4 N 4 + 2H 2 (). 



URIC ACID. 



This transformation of uric acid into hypoxanthine is of 

 especial importance, since together with HORBAC/EWSKI'S 

 synthesis of uric acid, accomplished by acting on urea with 

 either glyeocoll or trichlorlaetamide, it constitutes the last 

 step in the complete synthesis of hypoxanthine from its 

 dements. 



Hypoxanthine has l>een 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 from 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 xanthiue, 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 



