hatched and grows into a fowl. The animal, therefore, is produced by
the development of a germ in the same way as the plant; and, in this
respect, all plants and all animals agree with one another, and differ
from all mineral matter.

Thus there is a very broad distinction between mineral matter and
living matter. The elements of living matter are identical with those
of mineral bodies; and the fundamental laws of matter and motion apply
as much to living matter as to mineral matter; but every living body
is, as it were, a complicated piece of mechanism which "goes," or
lives, only under certain conditions. The germ contained in the
fowl's egg requires nothing but a supply of warmth, within certain
narrow limits of temperature, to build the molecules of the egg into
the body of the chick. And the process of development of the egg, like
that of the seed, is neither more nor less mysterious than that, in
virtue of which, the molecules of water, when it is cooled down to the
freezing-point, build themselves up into regular crystals.

The further study of living bodies leads to the province of biology,
of which there are two great divisions--botany, which deals with
plants, and zoölogy, which treats of animals.

Each of these divisions has its subdivisions--such as morphology,
which treats of the form, structure, and development of living beings,
and physiology, which explains their actions or functions, besides
others.

[Illustration]