514 ELIMINATION OF WASTE PRODUCTS. [Book ii. 



there leave the body a comparatively small quantity of salts, a 

 little carbonic acid, and a variable but on the whole large quan- 

 tity of water. 



The kidneys discharge all or nearly all the urea and allied 

 bodies, the greater portion of the salts, and a large amount of 

 water, with an insignificant quantity of carbonic acid. They 

 are especially important since by them practically all the nitro- 

 genous waste leaves the body, and to them we will turn first. 



