164 PHYSIOLOGY OF PURIN METABOLISM 



that all the objections raised by Schittenhelm and others are 

 unsound. ' ' I am compelled to remain of the same opinion as 

 before, believing it to be well founded and not contradicted ; 

 that is, that the changes in intermediate uric acid proceed in 

 man qualitatively precisely as in the other mammals, that is, 

 that it is transformed by oxidation into allantoin ; but quan- 

 titatively they lag behind so much that uric acid must be 

 regarded as the principal product of purin metabolism in 

 man." 



Wiechowski 's view has very recently received important 

 support from the results of a personal experiment conducted 

 by Lewinthal in Friedrich v. Muller's Clinic in Munich, 46 in 

 which the investigator injected into himself xanthin (dis- 

 solved in piperidin) and recovered the bulk (89 per cent.) in 

 the urine mainly as uric acid. Siven, in Helsingfors, 47 like- 

 wise concludes from experiments upon himself that the 

 human body is devoid of uricolytic ability and that purins 

 when they have once gained access to the circulation are to 

 be looked upon as end-products of metabolism. 



In connection with the exceptional position of man as to 

 purin metabolism it is instructive to note that the uricolytio 

 power of the tissues of the macacus rhesus species of 

 monkey is more like that of the tissues of other animals than 

 of human beings. 48 According to Wiechowski, in the lower 

 monkeys, as in other mammals, allantoin is the principal end- 

 product of purin metabolism. The urine of the chimpanzee, 

 however, corresponds in this particular with human urine. 49 



Decomposition of Purins in the Intestine. The fact 

 that dietary purins, whether free or combined, fail to 

 appear either as uric acid or allantoin in the urine can- 



** W. Lewinthal (F. v. Miiller's Clinic, Munich), Zeitschr. f. physiol. Chem., 

 77, 273-274, 1912. 



47 V. 0. Siv<5n (Helsingfors), Pfltiger's Arch., 145, 283, 1912. 



48 H. G. Wells (Chicago), Jour, of Biol. Chem., 7, 171, 1909-10. 

 * W. Wiechowski, Prager med. Wochenschr., 1912, 275. 



