342 CHEMISTRY OF THE LEUCOMAINS. 



The equations for adenin and hypoxanthin are not fully estab- 

 lished, but the bromin compounds are decomposed into alloxan. In 

 addition to this urea and oxalic acid are formed, both of which may 

 be derived from alloxan by decomposition, though some of the urea 

 may be independent of the breaking down of the alloxan group. 



Again, adenin and hypoxanthin on decomposition with concen- 

 trated hydrochloric acid yield the same products (glycocoll, ammonia, 

 formic and carbonic acids) as xanthin, guanin, etc. This decompo- 

 sition is best seen from the following equations : 



C,H,NP3 + 5Hp = 3NH3 + CjH,NO, + 3CO,. 



Uric Acid. 



C,H,Np, + 6H,0 = 3NH, + C,H,NO, + 2CO, + CH,0,. 



Xanthin. 



C^H^Np + 7H3O = 4NH3 + C,H,NO, + 2CO, + CHp,. 



GuAiriH. 



C^H^Np -I- 7H,0 = 3NH3 + C,H„Np + CO, + 2CH,0,. 



Htfozahthih. 



C„HA + 8H,0 = 4NH3 + C,H,NO, + CO, + 2CHA. 



ADiznu. 



Uric acid has no CH group, hence does not yield formic acid, 

 whereas xanthin and guanin have each one CH group and yield one 

 molecule of formic acid. Hypoxanthin and adenin therefore have 

 two CH groups. 



Furthermore, uric acid contains three CO groups and yields three 

 COj molecules, whereas xanthin and guanin have two CO groups 

 and yield two CO, molecules. Hence hypoxanthin has but one CO 

 group, since it yields but one CO, molecule. The corresponding car- 

 bon atom in adenin is likewise split off as carbonic acid. 



The changes which the purin bodies undergo in the animal econ- 

 omy have been the subject of numerous investigations. As is well 

 known, in birds the greater part of the waste nitrogen passes out in 

 the form of uric acid. This large amount of uric acid is derived 

 from two sources : (1) in small part from the nuclein metabolism of 

 the tissue ; (2) chiefly by synthetic transformation of simple nitrog- 

 enous substances. Thus, after the administration of urea or of 

 ammonium salts of organic acids birds eliminate uric acid. This 

 synthesis, according to Minkowski, takes place within the liver, since 

 after the removal of that organ the change does not take place. 

 Instead the administered nitrogen is excreted as ammonium salts 

 while the amount of uric acid falls to a minimum corresponding to 

 that formed by actual nuclein metabolism. 



In mammals on the other hand the purin bodies carry off" only a 

 very small part of the waste nitrogen. The chief if not the sole 

 source of the uric acid is tissue metabolism, since the recent studies 



