THE METABOLISM OF THE PURIN BODIES 409 



that it is. It may be of interest to give this table in its entirety 

 here. 



TABLE IV 



Grin, of Uric Ac.id-N or total Purin-N excreted per Diem. 1 



In other mammals than man, the proportion of ingested purin 

 which reappears in the urine may vary considerably. For example, 

 in dogs the purin excretion is much less proportionally, for about 

 ten times as much purin disappears in its passage through the 

 organism in the case of this animal as in the case of man ; 

 in rabbits three times as much disappears. Indeed, we have 

 every reason to believe that the amount which disappears, and 

 therefore the amount which passes into the urine, is not the same 

 for any two groups of animals, although it is probable that closely 

 related animals (cat and dog) excrete about the same fraction. 



We are now in a position to consider whether or not the purin 

 bodies produced in the tissues themselves (from nuclein break-down 

 and from the muscles) behave according to the same laws which 

 govern those of exogenous origin. In other words, does the amount 

 of endogenous purin excreted in the urine bear the same relation 

 to the amount of purin produced in the tissues, as the exogenous 

 purins in the urine bear to the purin of the food? 



In answering this question, we must first of all see whether 



1 Those marked * are calculated as uric acid-N. 



