EXCREMENTS AND URINE. 85 



clover hay, and in bread ; namely, one pound of azo- 

 tized to five or six of non-azotized ingredients. If 

 the use of oil-cake is preferred for the purpose of 

 strengthening the nutritious quality of weak fodder, 

 then, in order to realize the same proportion, about 

 two pounds of this substance should be employed 

 for one hundred pounds of beet-root, and about twice 

 that quantity for the same weight of potatoes. 



The question still remains to be answered. Which 

 constituents of the food, as also of those parts which 

 have become effete and unserviceable in the animal 

 body, are again removed from the living organism 

 by the solid excrements, and which in a liquid form 

 by the urine ? To this inquiry the general answer 

 may first of all be given : Whatever of these sub- 

 stances is capable of becoming fluid passes into 

 the urine, and whatever remains insoluble into the 

 solid excrements. This division, which will be dis- 

 cussed with greater precision in the following sec- 

 tion, is of very great importance, particularly in re- 

 spect of the mineral ingredients of the food, because 

 it is connected not merely with the quantities, but 

 also with the specific nature, of its constituents. 

 Of the organic overplus, the two main ingredients, 

 carbon and nitrogen, are voided in common by the 

 faeces and the urine ; the carbon in largest quantity 

 by the former, and the nitrogen to the extent of 

 nearly one half by the same channel, the remaining 

 half in the urine. On the other hand, it is altogether 

 different with the mineral constituents. Amongst 

 8 



