CHAPTEB I. XXIII 

 URIC ACID AND THE PURINE BODIES Cont'd 



SOURCE OF ENDOGENOUS PURINES 



Even after the entire eliminati t" all purine substances from the 



food in the ease of man, purine continues to be excreted in the urine 

 as uric arid. This, as above remarked, is called endogenous • tion. 

 At first it was thoughl by Burian and Schur thai the total nitrogen of 

 the purine-free diel could be considerably varied without causing any 

 alteration in the amounl of the endogenous purine excretion, but a rep- 

 etition of tli«' work lias shown that, when these changes are of consider- 

 able magnitude, the endogenous moiety does do1 remain constant. This 

 has already been demonstrated in the initio <>n Folin's results see p 

 614), and is still better illustrated in the accompanying table, which 

 shows Iho excretion of uric acid and coincidently of urea from hour to 

 hour in the urine after taking food which is free from nuclein or purine 

 substances. After a fasl of six hours, a diel consisting of bread and 



potatoes was taken at 1:30, and the urea and uric acid measured in the 

 urine each hour thereafter.* 



II ■■'•-.. - and II 



.1 postprandial increasi of endogenous purim ■ is very dis- 



tinct, and it indicates thai during the process of assimilation something 

 must be occurring in the organism which entails the production of pui 



• riu-sc in\ tuld l"- i 



i 



