to the Rearing and Feeding of Cdl.ile. 
225 
body, that moment the Chemical forces beffin the work of demo- 
lition on the unprotected part. Tims, if Vitality be called upon 
by the superior power, Volition, to execute some purpose of its 
will — to move the arm, for example — the vitality residing in the 
muscles of the arm obeys this command, and occasions the desired 
movement. Before the production of motion, all its powers were 
exerted in preventing the encroachment of the chemical forces 
(i.e. of the oxygen of the air). But when it is employed in 
effecting a vital movement, such as that of the arm, it is no longer 
in a position to resist the attack of its antagonist power. This, 
therefore, immediately acts upon the muscles, which obey the 
will, destroys part of their substance, and occasions its separation 
from the tissues. 
Probably none of Liebig's theories may appear so problemati- 
cal as that which asserts that every manifestation of force, however 
trivial, is accompanied by a change of matter in the body. Yet 
there is no theory which can be more easily proved by reference 
to your own experience. You are well aware that poultry-feeders 
confine their poultry when it is necessary to fatten them quickly. 
Tlie cruel practice of nailing the feet of geese to the ground 
during fattening is owing to the anxiety of avaricious feeders to 
prevent the expenditure of a particle of the food by the motion 
of the animal. The greatest part* of the food consumed by an 
animal thus deprived of the means of motion goes to the pro- 
duction of fat. When pigs are put up to be fattened, they are 
removed from the yard in which exercise is permitted, and placed 
in a narrow sty, with little room to move. A small amount of the 
food being now expended in the production of motion, the pig 
rapidly increases in size.f 
* Not all, because the involuntary motions, such as those of the heart 
and intestines, still proceed, and the heat of the body has to be sustained 
by the combustion of a portion of the food. 
+ An excellent proof of this view has been kindly pointed out to me by 
Mr. W. Stace, of Berwick, near Lewes. The experiment was performed by 
Lord Egremont about the end of the last centurj^ and is described in Young's 
Survey of Sussex in the following words : — 
" As there were some hogs that we wanted to keep over the summer, 
seven of the largest were put up to fat on the 23th of February ; they were 
fatted upon barley-meal, of which they had as much as they could eat. 
Some days after, the observation of a particular circumstance suggested the 
following experiment : — a hog nearly of the same size as the seven, but 
who had not been put up with them, because they appeared rather larger, 
but without weighing them, was confined on the 4th of March in a cage 
made of planks, of which one side was made to move with pegs, so as to 
fit exactly the size of the hog, with small holes at the bottom to allow the 
water to drain from him, and a door behind to remove the soil. The cage 
stood upon four feet, about 1 foot from the ground, and was made to con- 
fine the hog so closely that he could only stand up to feed and lie down on 
his belly. He had only two bushels of barley-meal, and the rest of his 
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