central telegraph-office, receiving impressions and sending messages to
all parts of the body, and putting in motion the muscles necessary to
accomplish any movement that may be desired. So that you have here an
extremely complex and beautifully-proportioned machine, with all its
parts working harmoniously together towards one common object--the
preservation of the life of the animal.

Now, note this: the Horse makes up its waste by feeding, and its food
is grass or oats, or perhaps other vegetable products; therefore, in
the long run, the source of all this complex machinery lies in the
vegetable kingdom. But where does the grass, or the oat, or any other
plant, obtain this nourishing food-producing material? At first it is
a little seed, which soon begins to draw into itself from the earth and
the surrounding air matters which in themselves contain no vital
properties whatever; it absorbs into its own substance water, an
inorganic body; it draws into its substance carbonic acid, an inorganic
matter; and ammonia, another inorganic matter, found in the air; and
then, by some wonderful chemical process, the details of which chemists
do not yet understand, though they are near foreshadowing them, it
combines them into one substance, which is known to us as 'Protein,' a
complex compound of carbon, hydrogen, oxygen, and nitrogen, which alone
possesses the property of manifesting vitality and of permanently
supporting animal life. So that, you see, the waste products of the
animal economy, the effete materials which are continually being thrown
off by all living beings, in the form of organic matters, are
constantly replaced by supplies of the necessary repairing and
rebuilding materials drawn from the plants, which in their turn
manufacture them, so to speak, by a mysterious combination of those
same inorganic materials.