i BIC ACID AM' i 111. PI BINE BODIES 6 15 



cretion of uric acid i n >>t <;i < ! of area. Everything which in a mammal 

 lends io cause an increase in urea excretion causes in birds and reptiles 

 a similar increase in the excretion of uric acid. 



In the earh days of research in the uric-acid problem, not inconsid- 

 erable mistakes were made on a »un1 of failure to recognize the 



lial difference in the metabolism of uric acid in birds and mammals. 

 and the tendency for some time after the exact state of affairs was 

 discovered was to consider thai in mammals none of this synthetic proc- 

 ess occurs. The Latter view, however, is surely incorrect, for a 

 linn amount not only of uric n< i<l itself but of th, lower purim boa 

 can I" produced by synthesis in th< mammalian body. Tims. Ascoli and 

 Izar 17 discovered that uric acid could be made either to disappear or 

 to be formed when a min 1 preparation of liver was incubated, depend- 

 ing upon whether oxygen or carbon dioxide was bubbled through it. 

 With oxygen uric acid disappeared, whereas with carbon dioxide uric 

 a.-id accumulated, indicating thai in the presence of this gas the destroyed 

 uric acid became reformed from the disintegration products of the oxy- 

 genation process. As similar results were obtained from the livi 

 birds, it is clear thai no essential difference exists between the purine 

 metabolic processes occurring in the livers of birds and of mamn 

 The difference is a quantitative not a qualitative one. 



Regarding the chemical nature of the product into which uric acid is 

 broken down and from which it may be resynthesized, it has been | 

 sible so far to identify but one substance — namely, dialuric acid. This 



is a perplexing result, for from all other investigations it would app< 

 that in mammals, with the exception of man and the anthropoid apes, 

 uricase splits uric acid into allantoine (see page 640), which substance, 

 however, when added to liver extract did not cause any uric acid to be 

 formed: nor did any of the other known decomposition products of uric 

 acid have such a result. The chemical reaction involved in the produc- 

 tion of uric acid from dialuric acid and urea is indicated as follows: 



s\i — c = o 



/ 

 / 

 / 



<> C • =H.OH H XII 



\ \ 



\ + c=o 



\ / 



Ml C II Ml 



i dialuric acid • 



The synthesis of uric acid is b rough 1 aboul bj the combined action 

 of a thermolabile enzyme in the blood and a thermostable body in the 

 tissues. An aqueous extract of hi I free liver of the <\"~ can destroy 



