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.

Let us trace out the history of the Horse in another direction. After
a certain time, as the result of sickness or disease, the effect of
accident, or the consequence of old age, sooner or later, the animal
dies. The multitudinous operations of this beautiful mechanism flag in
their performance, the Horse loses its vigour, and after passing
through the curious series of changes comprised in its formation and
preservation, it finally decays, and ends its life by going back into
that inorganic world from which all but an inappreciable fraction of its
substance was derived. Its bones become mere carbonate and phosphate of
lime; the matter of its flesh, and of its other parts, becomes, in the
long run, converted into carbonic acid, into water, and into ammonia.
You will now, perhaps, understand the curious relation of the animal
with the plant, of the organic with the in