A Book of Natural History | Page 7

hearts beat quicker; they leap, they swim, they swell out
their throats and call to each other in various keys. The toads are with
them, and the pretty tree-frogs that change their color to suit their
emotions. And all are rapturously screaming. Their voices are not
musical, according to man's standard, but seem to afford great
satisfaction to the performers in the shrill orchestra of the swamps, who
thus give vent to the flood of life that sweeps through them after the
still, icy winter.
As though the new spring-life were too plentiful to find room in the
frogs and toads already existing, it calls for more frogs and toads; and
new creatures are born to share the extra vitality. Like the flowers and
the fish, the frogs, too, give forth new life. Within them, too, the
miracle is performed. The tiny eggs of the one wake up and begin to
grow. The tiny living bodies in the fertilizing principle of the other also
wake up and begin to grow. But higher life is better guarded, because
less prolific. The frog and the toad lay but few eggs as compared with
the fish. Fish eggs may drop under the stones or float away, and so
escape the vital touch of the fertilizing principle. There are so many
that numbers may be lost and yet enough remain to continue the family.
Not so with the frog family. No egg may be lost. So we find that the
eggs of the frog are not dropped singly, like so many shot, but are
bound together by a colorless, transparent, jelly-like substance, much
like that found in the morning-glory seed, and which like that supplies
nourishment to the young life, for the tadpole feeds upon it until he is
able to seek other food. Moreover, instinct has taught the frog the need
of extreme caution in the act of fertilization. Every egg must be
fertilized. As the time draws near for the dropping of the few eggs into
the water, the male frog so places himself that the moment the eggs are
being laid, he pours over them, one by one, as they fall into the water,
the fertilizing fluid.

And thus the mystery of life is again repeated. The union of the living,
microscopic bodies of the fertilizing principle with the new laid egg is
followed by the growth of the two elements into a living creature, able
to eat, to breathe, to see, to feel. In some unknown way the atom of
fertilizing principle seems to have contained the whole life of the
father-frog, for it can give to his sons and daughters any of his
peculiarities, either of color, form, motion, or disposition; and the tiny
egg seems to have contained the whole life of the mother-frog, and can
give to her sons and daughters any of her peculiarities; though, as is
true of all inheritance, the tadpoles, as the young frogs are called, share
the natures of both parents, inheriting some peculiarities from the father
and others from the mother.
[Illustration: A FROG.]
But, like other life, although the frogs may vary a good deal within frog
limits, none of them can escape their own limits and enter into those of
any other life. Once a frog, always a frog; and no frog-egg may hope to
develop into a turtle, or a bird, or anything but a frog. The life in the
fertilizing principle of the frog is sacred to frog eggs, and is lifeless in
contact with any other.
Our common frogs, like many of the fishes, do not trouble themselves
about the fate of their eggs after they are carefully laid in a safe place.
They trust Mother Nature to see the little tadpoles safely through the
perils of childhood, to help them change their dresses and get rid of
their tails, and cut, not their teeth, but their arms and legs.
In Venezuela, however, there dwells a frog with well developed
maternal instinct. The mothers have pockets on their backs, not for
their own convenience, but as cradles for their babies. The fathers put
the fertilized eggs into the pockets of the mothers; and there they
remain, well guarded, until the young are able to care for themselves.
[Illustration: TADPOLES.]

THE MAN-LIKE APES
(FROM EVIDENCE AS TO MAN'S PLACE IN NATURE.)
BY PROFESSOR T. H. HUXLEY.
[Illustration: HEAD OF GORILLA.]
Sound knowledge respecting the habits and mode of life of the
man-like Apes has been even more difficult of attainment than correct
information regarding their structure.
Once in a generation, a Wallace may be found physically, mentally,
and morally qualified to wander unscathed through the tropical wilds of
America and of Asia, to form magnificent collections as he wanders,
and withal to think out sagaciously the conclusions suggested by