EXCRETION 279 



diminished in severe disease of that organ, such as 

 acute yellow atrophy, its place being taken by salts of 

 ammonia and amino-bodies. As it is merely picked out 

 of the blood by the kidneys, it accumulates in the 

 circulation in cases of severe impairment of renal 

 function, and, being very soluble, may be found in any 

 of the secretions e.g., the sweat. 



Uric Acid. The origin of the uric acid in the urine 

 has been considered in a previous chapter (p. 45), but 

 it must again be emphasized here that its amount is 

 very largely dependent upon the amount of purin bodies 

 in the food, and that it bears no constant ratio to urea. 

 The influence of diet is shown by the following figures 

 (von Noorden) : 



Daily excretion of uric acid on a ' purin- 



free'diet 0'25 to 0'6 gramme. 



Daily excretion of uric acid on a mixed 



diet 0'5 to 1 gramme. 



Daily excretion of uric acid on a largely 



meat diet 1 to 1 or 2 grammes. 



Ammonia. The amount of ammonia excreted in the 

 urine may be taken as an index of the amount of acid 

 entering the circulation, for it is by the neutralization 

 of acid by carbonate of ammonia that the body protects 

 itself against 'acidification.' The amount is therefore 

 greater on an animal than on a vegetable diet, whilst 

 in some pathological states, such as in the later stages 

 of diabetes, and in some of the toxaemias of pregnancy, 

 when organic acids are entering the blood in large 

 quantities, the excretion of ammonia may rise enormously. 



Of the remaining nitrogenous constituents, creatinin 



