OXIDATION OF URIC ACID. 137 



addition of the elements of water, all the elements 

 essential to this metamorphosis ; and, except the 

 sulphur and phosphorus, both of which are probably 

 oxidised, no element is separated. 



This form of metamorphosis is applicable to the 

 vital transformations in the lower classes of amphi- 

 bia, and perhaps in worms and insects. In the 

 higher classes of animals the uric acid disappears in 

 the urine, and is replaced by urea. 



The disappearance of uric acid and the production 

 of urea plainly stand in a very close relation to the 

 amount of oxygen absorbed in respiration, and to 

 the quantity of water consumed by different animals 

 in a given time. 



When uric acid is subjected to the action of 

 oxygen, it is first resolved, as is well known, into 

 alloxan and urea. (32) A new supply of oxygen 

 acting on the alloxan causes it to resolve itself 

 either into oxalic acid and urea, into oxaluric and 

 parabanic acids, (33) or into carbonic acid and urea. 



32. In the so-called mulberry calculi we find 

 oxalate of lime, in other calculi urate of ammonia, 

 and always in persons, in whom, from want of ex- 

 ercise and labour, or from other causes, the supply 

 of oxygen has been diminished. Calculi containing 

 uric acid or oxalic acid are never found in phthisical 

 patients ; and it is a common occurrence in France, 

 among patients suffering from calculous complaints, 

 that when they go to the country, where they take 

 more exercise, the compounds of uric acid, which 



