_FROM TADPOLE TO FROG._
[Illustration]
1. In the spring of the year the frog lays its eggs in the water.
These eggs are small and round, but soon swell out to the size of a
large pea. Each egg has in it a black speck, not much larger than a
pin's head.
2. This speck grows, and in the course of a few days out comes a
tadpole about half an inch long. Now, a tadpole has a round head,
with a flat tail on one side, but no body.
3. The tadpole can swim with its tail, like a fish. On each side of
the head is a small tuft of soft pink threads. These are gills,
through which it can breathe the air which is in the water.
4. Then the body grows, and in a short time two little legs come out
right where the tail joins the body. In a few days more two other legs
come out just back of the eyes, and then we have a tadpole with four
legs.
5. But now another change takes place. Lungs for breathing air begin
to grow inside, and the gills become smaller. For a time the tadpole
breathes partly in the water, with his gills, and partly in the air,
with his lungs.
6. Next the gills dry up, and then it comes to the top of the water to
breathe; and it looks very much like a frog, except that it has a
tail.
7. At last the tail shrinks away, and the tadpole has become a perfect
frog. In hot weather all these changes take place in a few weeks; but
when it is cold, they take a longer time.
8. The frog, when full grown, can live on the land or in the water. It
can stay under water some time, but must come to the top to breathe.