Because it has attached to its body a fringe of muscular skin, which is capable of considerable contraction and expansion, and by alternately stretching and shortening this, the snail is able to draw himself along.
1311. Why do we see no snails in the winter time?
Because they bury themselves in the ground, or in holes, where they remain in a torpid state for several months. Before they enter into the torpid state, they form with their slimy secretion, and with some earthy matters which they collect, a strong cement with which they seal up the opening to their shells.
1312. Why can snails live in shells thus sealed?
Because they leave, in the thin wall by which they close themselves in, a small hole, too small to admit water, but large enough to let in sufficient air to carry on their feeble respiration during their winter sleep.
1313. Why do insects abound in putrid waters, and in decaying substances?
Because they have been endowed with appetites and with constitutions that enable them to live upon and to enjoy corrupt matter. In this point of view the maggots of flies are exceedingly useful; a dead carcass is speedily threaded by them in every direction; thus that corrupt matter which, in a large mass, would poison the air, is taken up in small portions by millions of living bodies, and by them dispersed, and becomes innoxious.
"For he maketh small the drops of water: they pour down rain according to the vapour thereof."—Job xxxv.