ants 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 zooelogy, 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]

LIFE GROWTH;--FROGS

(FROM A SONG OF LIFE.)

BY MARGARET WARNER MORLEY.[1]

[1] Copyright by A. C. McClurg & Co., 1891.

[Illustration]

Somewhat higher than the fish in the scale of life is the frog.
Although he begins life as a fish, and in the tadpole state breathes
by gills, he soon discards the water-diluted air of the pond, and with
perfect lungs boldly inhales the pure air of the upper world. His life
as a tadpole, although so fish-like, is much inferior to true fish
life: for though the fish has not the perfect lung, he has a
modification of it which he fills with air, not for breathing
purposes, but as an air-sac to make him float like a bubble in the
water. Will he rise to the surface? he inflates the air-bladder. Will
he sink to the bottom? he compresses the air-bladder. But in the frog
the air-bladder changes into the lungs, and is never the delicate
balloon which floats the fish in aqueous space. When the frog's lungs
are perfected, his gills close, and he forever abandons fish-life,
though being a cold-blooded creature he needs comparatively little
air, and delights to return to his childhood's home in th