48 APPLIED PHYSIOLOGY 



source of uric acid in the body is the form in which it 

 circulates in the blood. Now, it is a curious fact that, 

 although the administration of purins is followed by an 

 increase in their excretion, yet mere traces of purins can 

 be discovered in the blood in health. It has therefore 

 been suggested that they circulate in a combination 

 possibly with proteins which prevents them from 

 giving the usual reactions (just as iron is masked by its 

 combination in haemoglobin); and another thinkable 

 hypothesis to explain gout is that in the gouty indi- 

 vidual this combination is for some reason not formed, 

 and that uric acid circulates as urates, a form in which 

 it is with difficulty excreted. 



Finally, it has been ascertained that in health the 

 subcutaneous injection of uric acid, or its excessive 

 ingestion in the form of purins, is accompanied by an 

 increased excretion in the urine ; but prolonged examina- 

 tion of the urine in gout shows that the excretion of uric 

 acid is not greater than normal. It seems to follow from 

 this that the excess of urates in the blood in gout must 

 be due to diminished excretion, and not to increased 

 ingestion of exogenous, or increased production of endo- 

 genous, uric acid. 



