344 CHEMISTRY OF TEE LEUCOMAINS. 



by the action of the crushed liver is changed to uric acid. In beef- 

 liver, however, Wiener obtained an alcohol-soluble antecedent which 

 was not a purin. It is very doubtful as to whether uric acid can 

 thus be synthesized from urea, glycocoU and similar compounds. 

 One fact is evident and that is that uric acid and hence other purin 

 bodies are broken down in the body and that this change takes place 

 especially in certain organs. 



The amount of uric acid actually carried to the kidneys to be 

 eliminated (a) therefore will be the algebraic sum of that formed in 

 nuclein metabolism (x) (tissue and food), that formed by synthesis 

 (y), and that destroyed in the body (z). Thus, 



X -\- y — z = a. 



The actual amount of uric acid eliminated, however, may be con- 

 siderably less than that represented by a since the kidney may be 

 incapable of effecting the complete excretion. In which case de- 

 posits of uric acid will occur in the joints, as in rheumatism ; and in 

 the kidneys as in adenin poisoning and in the kidney infarcts of the 

 new-born (Spiegelberg). 



The purin bases may be looked upon as undergoing changes 

 similar to those of uric acid. Hypoxanthin apparently is the only 

 member of the group which when fed to birds, dogs or man (Min- 

 kowski) is eliminated as uric acid or as its cleavage product allantoin. 

 Moreover the crushed beef liver is capable of effecting this conversion 

 into uric acid (Wiener). Adenin on the other hand in dogs does 

 not give rise to uric acid or to allantoin. A small amount appears 

 in the urine unchanged (Kossel, Minkowski) the remainder being 

 undoubtedly broken up into simple products. It is significant that 

 the thymus gland which is rich in an adenin-producing nuclein 

 should increase the amount of uric acid and even give rise to allan- 

 toin, whereas adenin itself is without this effect. It may be that the 

 adenin while still in a nascent condition, as it were, is more readily 

 oxidized than when definitely formed. At all events its antecedent 

 behaves quite differently. 



According to Kriiger and Schmid ^ the purin bases when admin- 

 istered to man are largely eliminated as uric acid. Thus, 62.3 per 

 cent, of the hypoxanthin given was excreted as uric acid and only 

 0.15-0.25 per cent, as purin bases. Adenin gave a similar result, 

 40.7-41.2 per cent, appearing as uric acid and 2.6-3.7 per cent, 

 being unchanged. With xanthin 10 per cent, formed uric acid and 

 1 per cent, was eliminated unchanged. Guanin perhaps also yields 

 uric acid but this is not definitely settled. 



Nothing definite can be said regarding the fate of xanthin and 

 guanin in the animal body. It has been shown in pancreatic and 



^Zeiis. phyM. Chem., 34, 549, 1902. 



