160 PHYSIOLOGY OF PURIN METABOLISM 



with protoplasmic poisons (hydrazin, hydroxylamine and 

 semicarbazide) as well as in autolysis, as repeatedly observed 

 by Boris-sow and by J. Pohl and his collaborators. 31 



In what organs the change from uric acid into allantoin 

 takes place is not known ; that it is not limited to the liver is 

 proved by observations on dogs with Eck's fistulas. 32 



While parenterally introduced nucleinic acid is appar- 

 ently changed practically completely into allantoin by the 

 mammalian body, this is not by any means always the case 

 with the nucleinic acid introduced by the mouth. In rabbits 

 only half or less of the nitrogen of the bases appears as 

 allantoin in the urine under such circumstances. According 

 to Wiechowski this may be easily explained by the fact that 

 in the alkaline intestinal contents extensive destruction of 

 allantoin takes place, apparently without necessity for inter- 

 vention of bacteria, but certainly with such aid. On the 

 other side of the intestinal wall, however, the allantoin is a 

 stable product. 



Fate of the Intermediary Uric Acid in Man. As far as 

 uricolysis in the lower animals is concerned there is a fair 

 unanimity of opinion; the more divergent, however, the 

 opinions as to the destruction of uric acid in human 

 metabolism. 



For a decade the physiology and pathology of purin 

 metabolism remained unchanged under the domination of 

 the hypothesis that a marked destruction of uric acid takes 

 place in the human body. In conditions in which (as in gout) 

 special accumulation of uric acid was assumed to exist, the 

 fault was always referred to some lowering of the power of 

 the tissues to destroy uric acid. In the course of the last 

 few years these ideas have undergone appreciable change. 



Absence of Uricase in Human Tissues. As has been 

 said, uric acid destruction, with formation of allantoin, 



"Literature: W. Wiechowski, Hofmeister's Beitr., 9, 306, 1907. 

 M E. Abderhalden, E. S. London and A. Schittenhelm, Zeitschr. f. physiol. 

 Chem., 61, 413, 1909. 



