FROM THE METAMORPHOSED TISSUES. 139 



severe and continued exertion, more urea is secreted 

 than in the most highly fed individual, if in a state 

 of rest. In fevers and during rapid emaciation the 

 urine contains more urea than in the state of health. 

 (PROUT.) 



33. In the same way, therefore, as the hippuric 

 acid, present in the urine of the horse when at rest, 

 is converted into benzoate of ammonia and carbonic 

 acid as soon as the animal is compelled to labour, 

 so the uric acid disappears in the urine of man, 

 when he receives, through the skin and lungs, a 

 quantity of oxygen sufficient to oxidise the products 

 of the transformation of the tissues. The use of 

 wine and fat, which are only so far altered in the 

 organism that they combine with oxygen, has a 

 marked influence on the formation of uric acid. 

 The urine, after fat food has been taken, is turbid, 

 and deposits minute crystals of uric acid. (PROUT.) 

 The same thing is observed after the use of wines 

 in which the alkali necessary to retain the uric acid 

 in solution is wanting, but never from the use of 

 Rhenish wines, which contain so much tartar. 



In animals which drink much water, by means of 

 which the sparingly soluble uric acid is kept dis- 

 solved, so that the inspired oxygen can act on it, no 

 uric acid is found in the urine, but only urea. In 

 birds, which seldom drink, uric acid predominates. 



If to 1 atom of uric acid we add 6 atoms of oxy- 

 gen and 4 atoms of water, it resolves itself into urea 

 and carbonic acid : 



