1894.] Animal Mechanics. 559 
0 — — 1 — Bored in increase. | Voided in Excreta. 
d si Food. 
Oxen. | Sheep. | Pigs. | Oxen. | Sheep. | Pigs. 
$ 
Ibs Ibs Ibs Ibs Ibs Ibs 
otei | 41 4.2 13.5 95.9 | 95.8 | 86.5 
Non-proteids 1 2:29 i | IM 143. 1. 84 | 
Hie XM | 1-9 T Ww T 38 | ww» | wr Ww 
Bubeame | 621. | RA | dM | MÀ ( WH9 | M 
The food constituents not accounted for have served a use- 
ful purpose in their liberated energy for the performance of 
work, and their residues have been exhaled in the gaseous 
form, and the surplus energy as animal heat. Growing ani- 
mals, and cows giving milk, will retain, or utilize a larger 
proportion of the food constituents, but even then much the 
larger part of the material elements of the food are discharged 
in the excreta. 
In the next place, the potential or stored energy of the food 
is made available in all of the work done by the system, and 
it is the sole source of power in all of the processes of the ani- 
mal machine. 
From the prominence given to the chemical theory of nutri- 
tive ratios in some of our agricultural papers, farmers are 
asked to believe that success in feeding depends upon follow- 
ing certain theoretical formulas, giving the proportions of food 
constituents in the rations fed, while the animal machine 
which does the work of manufacturing valuable animal pro- 
ducts, and the motive power that makes it efficient, are 
entirely ignored. I can only say in passing, that in the pres- 
ent state of knowledge, we cannot formulate the constituents 
of foods in chemical terms, to serve as practical guides in 
feeding. The machine itself, is the most important considera- 
tion, and its capacity, for doing the work required of it, is of 
far greater significance than the proportions of the compara- 
tively small amount of the so-called nutritive constituents 
stored up, or used by the animal. 
Let us for a moment consider the facts in regard to the con- 
struction and repair of other farm machinery, as reapers, 
mowers, threshing machines, etc. When we-take an exact 
inventory of the items of cost, in the construction and repair 
of these machines, we find that the materials of which they 
. are made, or are used in repairing them, make but a small fig- 
