They have gills, which enable them to breathe in water, to begin with, and lungs which enable them to breathe in air, later on. They are mostly without scales, and do not need to drink, because they imbibe moisture from the air through their soft damp skin. When you see a frog hopping across your path, you see a creature which has known many a change in its life, for frogs are among those very interesting animals which undergo what are called metamorphoses. We have met with this word before, and may remember that it is used to express the change from one form to another which is wrought in some living creatures in the course of their growth. I daresay you imagine as I once did, that all young animals are like their parents, only on a smaller scale; for you see that a young horse, or elephant, or whale, a pup or a kitten, is at its birth in all respects just what it will be when full-grown, only smaller. So it is with the reptiles and the birds—the young ones, when hatched, are like the parents. But in the case of frogs and newts, and also most insects, the young ones do not merely increase in size as they grow, but pass from one stage of growth to another, each different from the former, until like the butterfly when it emerges from the chrysalis, they reach what is called their perfect state—and these metamorphoses or changes are very curious and interesting indeed.
When Master Froggie was a young tadpole, some pond or ditch was his home, for he was an aquatic animal; but now that he is full-grown he has passed into another way of living: he breathes, or rather swallows air, and must, as he swims about with his beautifully webbed feet, come to the surface of the water now and then, or he would die. I am sure you know the frog well enough, and you may even have heard the harsh croak from which it has its name, as you have passed some damp meadow or weedy pond, on a summer evening. But I wonder whether you know frogs' eggs when you see them?
My brothers and I did not, long ago, when we used to fish with sticks in a pond by the cross-roads for what we called "bunches of grapes!" The grapes were little balls of jelly with a tiny black spot in each, and we never guessed that they were really eggs, and that the little black spot in the slimy covering would one day actually turn into a live, leaping, croaking frog. If we had had the patience to watch, we should have seen that little black dot grow and grow, until it seemed to have become a creature almost all tail, with the head and body still only a tiny ball. By-and-by we should have seen legs and feet begin to appear, and as the legs grew longer, the tail become shorter, until it quite disappeared. Meanwhile, other changes which we could not see would have taken place; instead of the gills, which made the tadpole a water-breather, Master Froggie would have acquired lungs, like any land animal; the aquatic would have changed into an aërial, the herbivorous into a carnivorous creature, so that we may well say it has lived two lives.
The beautiful little newts' life-history is much the same, only that their transformation is not quite so complete, for they never lose their lizard-like tails, but remain little crocodiles to the end of the chapter.
"Be ye therefore merciful, as your Father who is in heaven is merciful."
"Turn, turn thy hasty foot aside,
Nor crush that helpless worm;
The frame thy wayward looks deride
None but our God could form.
"The common Lord of all that move,
From whom thy being flow'd,
A portion of His boundless love
On that poor worm bestow'd.
"The light, the air, the dew He made
To all His creatures free,
And spreads o'er earth the grassy blade
For them as well as thee.
"Let them enjoy their little day,
Their lowly bliss receive;
Oh! do not lightly take away
The life thou can'st not give."