EXCREMENTS AND URINE. 79' 



some have the greatest similarity to the blood and 

 flesh, others to the fat, others, again, to the bones. 

 Hence we infer that these vegetable constituents are 

 actually converted in the animal body into blood, 

 flesh, fat, and bones. 



Of the above-stated constituents of the potato^ 

 the vegetable fibre and starch have great similarity 

 and almost identical composition with the fat of ani- 

 mals ; the albumen, with the blood and flesh ; and 

 the mineral substances, with the bones. 



A very large portion, however, of the food given 

 to an animal disappears, as is universally known, 

 during its passage through the body ; for the dried 

 fsBces and urine weigh conjointly but from one third 

 to one half as much as the food in a similarly dry 

 condition. To know which elements of the food 

 pass off in this manner, — partly through the skin, as 

 perspiration or sweat, partly through the lungs and 

 mouth, as air or breath, — must of course be extreme- 

 ly important in forming an opinion concerning the 

 nutrient power of the aliment, and also concerning 

 the strength of the manure that is generated from it. 

 The following results have been deduced from those 

 experiments which have been made, up to the present 

 time, in regard to these points : — 



