f
crackers or bread, and bits of raw meat or fish being very acceptable.
If they are well fed on meat or fish, they will grow faster and change
earlier into frogs. Indeed, by underfeeding tadpoles a person can keep
them a whole year from undergoing the changes they would have normally
undergone in a few weeks. The large bull-frog tadpoles naturally take
two years to develop, though a very nutritious diet may possibly hasten
them.

[Illustration: TADPOLES AT DIFFERENT STAGES OF GROWTH]

The tadpole has very small eyes, a very small mouth, and tiny gill
openings like a fish. Indeed, so far as its life at this stage is
concerned, to all intents and purposes it is a fish. It cannot live out
of the water, it breathes by gills, it swims by its tail, but it has no
fins. It wiggles about the jar or tank in a very lively way, and ought
to have water weeds or stones to hide under, and pebbles or gravel in
the bottom of the receptacle.

The ordinary tadpole, if well fed, astonishes and delights his young
keepers in a few days by putting forth a pair of tiny hind legs, which
generally trail behind him when he swims, though he often kicks with
them, perhaps for exercise. He grows larger and his legs longer, and one
day a row of fingers may be seen peeping out of his gill slit, as though
out of an armhole, and then he will thrust out a forearm, then another
from the other gill slit. After this, changes are rapid, and his keepers
should put a stone or some firm object in the water, reaching above the
surface, so that he can climb up into the air; for now his lungs are
rapidly forming, and soon he can no longer breathe by gills. At this
stage, his tail begins to disappear. It does not fall off, as some
think, but its substance is absorbed into his body until no tail is
left. Finally, his head changes its shape, his baby mouth is replaced by
a wide frog mouth, his eyes stand out with projecting lids, his
ear-plates showing back of them, and we have a full-grown frog.

To the child who understands the origin of the fish eggs a few
questions which he can easily answer himself will be enough to call
attention to the important differences, and also to deepen the
impression of the unity of life as expressed in flower, fish, and frog.
The ova of the frog develop in an ovary exactly as do the ova of a fish;
they develop in the same way and at the maturity of the animal. The
fertilizing cells develop like those of the fish. In both cases, t