138 URIC ACID AND UREA DERIVED 



were deposited in the bladder during their residence 

 in town, are succeeded by oxalates (mulberry calcu-* 

 lus), in consequence of the increased supply of oxy- 

 gen. With a still greater supply of oxygen they 

 would have yielded, in healthy subjects, only the 

 last product of the oxidation of uric acid, namely, 

 carbonic acid and urea. 



An erroneous interpretation of the undeniable 

 fact that all substances incapable of farther use in 

 the organism are separated by the kidneys and ex- 

 pelled from the body in the urine, altered or 

 unaltered, has led practical medical men to the 

 idea, that the food, and esj^ecially nitrogenised food, 

 may have a direct influence on the formation of 

 urinary calculi. There are no reasons which support 

 this opinion, while those opposed to it are innume- 

 rable. It is possible that there may be taken, in 

 the food, a number of matters changed by the 

 culinary art, which, as being no longer adapted to 

 the formation of blood, are expelled in the urine, 

 more or less altered by the respiratory process. But 

 roasting and boiling alter in no way the comj)osition 

 of animal food. (34) 



Boiled and roasted flesh is converted at once into 

 blood; while the uric acid and urea are derived 

 from the metamorphosed tissues. The quantitv of 

 these products increases with the rapidity of trans- 

 formation in a given time, but bears no proportion 

 to the amount of food taken in the same period. In 

 a starving man who is any way comi^elled to undergo 



