448 



PHYSIOLOGY. 



Burian holds that hypoxanthin must be continually produced 

 in the muscles, and that this production is increased by muscular 

 contraction. Before it enters the blood it is converted by xanthin- 

 oxidase into uric acid. 



Uric acid has two origins, exogenous and endogenous. The 

 exogenous origin is from the foods containing nuclein or purin sub- 

 stances. 



The endogenous uric acid comes from the metabolism of all 

 cells, but especially from the nuclein of the leucocytes; hence it is 

 especially increased in the disease where there is an excess of leuco- 

 cytes, leucocythaBmia. 



Fig. 171. Urate of Soda and Crystals of Uric Acid (h), Oxalate of 

 Lime ( o ) , and Cystin ( c ) . X 350. ( LENHABTZ. ) 



Want of exercise leads to an increased formation of uric acid 

 by a lessening of the oxidation of the tissues. 



In gout the amount excreted in the urine is small, while it 

 accumulates in the blood and tissues. 



In the gouty deposits about the joints the so-called "chalk 

 stones'' contain 50 per cent, of sodium urate. 



Uric acid probably circulates in the blood chiefly as a mono- 

 natrium urate or in combination with an organic acid. 



Uric acid and lithic acid are the same. Lateritious, or brick-dust, 

 sediment in the urine is composed of urates, and is chiefly sodium 

 urate. 



The average daily quantity of uric acid passed in the urine of 

 man might be calculated at about 7 grains. When the quantity is 



