Eggs laid by the snake are also of frequent occurrence. I have found them in manure heaps, the warmth of which places is attractive to them. The eggs are white, and covered with a strong membrane, but have no shell. They are laid in long strings, from sixteen to twenty eggs being in each chain.
In the winter the ringed snake retires to a convenient cell, such as a hollow tree, or a heap of wood, and there it remains in a torpid state until the warm weather. Many individuals have been found collected together in these winter quarters, probably for the sake of affording each other mutual warmth.
The reptiles of which we have just treated live exclusively on land, though they may occasionally be found in water; but those which we shall now inspect belong rather to the water than to the land. The most common of these amphibious reptiles, as they are called, is the Frog.
A very curious animal is a frog, and well worth examining, as well in its perfect state as in its intermediate state. To begin at the beginning of a frog’s existence, we find it exhibited in masses of eggs, fixed to each other by a kind of gelatinous substance, and floating in large quantities in ditches or ponds. Each egg is about the size and shape of a pea, and in the centre is the little black speck from which the young frog proceeds.
In process of time the egg is hatched, and out comes a queer little creature, with a big head and a flat slender tail, called generally a tadpole, and in some places a pollywog. In this state of life the young creature is simply a fish, with fish-like bones, and breathing through gills, after the manner of fish.
Being very voracious, it grows rapidly: little legs begin to show themselves; and, at the proper season, the gills are laid aside, the tail vanishes, and the little frog is then in its usual form. The circulation of the blood can be well exhibited by means of a microscope, if a tadpole be laid on the stage so as to bring its tail within the focus, care being taken to keep that member well wetted.
At the time when the tail is laid aside, the young frog is very small, and in this state is generally found to swarm immediately after rain. The frog-showers, of which we so often hear, are probably occasioned, not by the actual descent of frogs from the clouds, but from the genial influence of the moisture on the young frogs who have already been hatched and developed, and who have been biding their time before they dared to venture abroad.