AND OTHER URINARY DEPOSITS 85 



purin bodies. Calf's thymus, the roe of fishes, liver, 

 and pancreas (sweetbread), all have this effect. To 

 sum up, uric acid and other purin bodies are derived 

 from feeding on : 



1. Purin bodies in meat, broths, coffee, etc. 



2. Nucleoproteins. 



Strange to say, feeding on uric acid itself causes no 

 increased output in the urine ; instead, there is a 

 greater excretion of urea. If urates are injected into 

 the blood-stream, uric acid and urea are both in- 

 creased in the urine, only part of the uric acid injected 

 being recovered as such. Evidently then some organ 

 is capable of converting uric acid into urea. This 

 organ is the liver, and a uricolytic ferment, destroying 

 uric acid, may be obtained from it. 



The whole of the purin body given by the mouth 

 does not appear as purin body in the urine. A good 

 deal appears as urea. There is a fraction, constant 

 for the species, representing to what extent this takes 

 place. In man, half the purin body absorbed is 

 destroyed by the liver. In the dog, nineteen- 

 twentieths are destroyed. The difference appears to 

 depend on the differences in relative size of the 

 blood-vessels of the liver and kidney in the various 

 species, those of the dog's liver being very large. 



It has yet to be explained how it is that adenin 

 and guanin derived from nucleoprotein and xan- 

 thin and hypoxanthin derived from muscle come 

 to be excreted partly as urea, partly as uric acid, and 

 partly as less oxidized purin bodies. 



It is now known that many organs of the body, 

 notably the spleen, contain a remarkable series of 



