THE METABOLISM OF THE PURIN BODIES 419 



Wiener. 1 He found that extracts of the kidneys and, to a 

 less extent, of the muscles of herbivorous animals are capable 

 of decomposing uric acid, the end products being not allan- 

 toin but glycin. Similar extracts of the livers of the same 

 animals were found to possess no power of destroying uric acid 

 but rather of producing it, 2 for, after incubation for some hours, 

 uric acid was found to have accumulated in the extracts. As we 

 have already seen, Horbaczewski and Spitzer ( 10 ) had pre- 

 viously observed the same accumulation of uric acid when a 

 mixture of liver pulp and blood of oxen was allowed to stand 

 some time. These latter facts are mentioned here to indi- 

 cate how undefined at present is our knowledge of the site of 

 uric acid formation and destruction in animals of different habits. 

 So much, however, we may take as certain, that in dogs the liver 

 is the organ possessed of any considerable power of destroying uric 

 acid, and this is all that we require to know for our present 

 purpose. 



To return to Burian and Schur's experiments regarding the 

 intermediary nature of (endogenous) purins: we are now in a 

 position to see which of the two explanations offered on p. 417 to 

 explain the disappearance of uric acid from the blood of nephro- 

 tomised dogs is the correct one. If, in these dogs, the liver as 

 well as the kidneys be excised, and we find uric acid to accumulate 

 in the blood, we can, with confidence, discard the hypothesis which 

 supposes endogenous uric acid to be produced in the kidneys, 

 and must accept that which supposes it to be, like the exogenous 

 moiety, capable of further destruction in the body. To exclude 

 both the kidneys and the liver from the circulation, Burian and 

 Schur placed a ligature on the aorta immediately above the 

 coeliac artery. Such a ligature cuts of! from the general circula- 

 tion any blood coming from the intestines, and so excludes any 

 absorption of exogenous purins. As it was shown in a control 

 experiment that there might be some exogenous purins in the 

 blood before the ligature was applied, and as the experiment 

 concerns the endogenous moiety, the precaution had to be taken 

 to feed the dog on a purin-free diet for some time before the 



1 Weiner made extracts of various organs and tissues with isotonic salt 

 solution, added uric acid to these extracts and placed them on a shaker in 

 the incubator for several hours. 



2 Burian has recently shown, however, that the liver of the ox does possess 

 some power of destroying uric acid, especially if the uric acid be in solution 



