ple visual apparatus serves them
only in distinguishing light from darkness, but this to them is most
important knowledge, as it enables them to avoid the surface of the
earth by day, when their worst enemies, the birds, are in active
search for them.

The fresh-water mussels and snails and the crayfish burrow deep into
the mud and silt at the bottom of ponds and streams where they lie
motionless during the winter. The land snails, in late autumn, crawl
beneath logs, and, burrowing deep into the soft mould, they withdraw
far into their shells. Then each one forms with a mucous secretion two
thin transparent membranes, one across the opening of the shell and
one a little farther within, thus making the interior of the shell
perfectly air-tight. There for five or six months he sleeps, free from
the pangs of hunger and the blasts of winter, and when the balmy
breezes of spring blow up from the south he breaks down and devours
the protecting membrane and goes forth with his home on his back to
seek fresh leaves for food and to find for himself a mate.

Next in the scale come the insects, which comprise four-fifths of all
existing animals, and each one of the mighty horde seen in summer has
passed the winter in some form. One must look for them in strange
places and under many disguises; for they cannot migrate, as do the
majority of the birds, nor can they live an active life while the
source of their food supply, the plants, are inactive.

The majority of those insects which in May or June will be found
feeding on the buds or leaves of our trees, or crawling worm-like over
the grass of our lawns, or burrowing beneath the roots of our garden
plants, are represented in the winter by the eggs alone. These eggs
are deposited in autumn by the mother insect, on or near the object
destined to furnish the young, or larvae, their food. Each egg
corresponds to a seed of one of our annual plants; being, like it,
but a form of life so fashioned and fitted as to withstand for a long
period intense cold; the mother insect, like the summer form of the
plant, succumbing to the first severe frost.

Thus myriads of the eggs of grasshoppers are in the early autumn
deposited in the ground, in compact masses of forty to sixty each.
About mid-April they begin to hatch, and the sprightly little insects,
devoid of wings, but otherwise like their parents, begin their
life-work of changing grass into flesh.

[Illustration: HEDGEHOG CATERPILLA