me line in
which it was proceeding, it would not become a quadruped, but it would
be an anomalous creature somewhat like one. Consequently, no one species
now on the earth can have been evolved out of any other existing race;
because the germs of any two, at a very early stage in their history,
according to our author's own confession, are specifically unlike.

To avoid this difficulty, he is driven to a further supposition, still
more gratuitous and improbable; namely, that the germ destined to become
one of a different race from its parents, having advanced along its
usual line of development so far as that line coincides with the one
belonging to the new species, there diverges, and follows a different
path up to the period of its birth into a new creature; that is, the
embryo of a reptile, having grown for a certain time as if it were to be
a reptile, suddenly turns aside, like a young man changing his mind
about the choice of a profession, and for the rest of its foetal life
follows the proper line of progress in order to be developed into a
bird. This is mere dreaming, and reminds one only of the wonderful
transformations effected by enchantment in an Arabian tale. We might
just as plausibly suppose, that the reptile, after it became mature, was
suddenly transformed into a bird, as that it underwent this change
before it was hatched. All the evidence attainable goes to show, that
the law of development is as immutable before as after birth, the
several stages of progress succeeding each other in a constant order,
and affecting the individual only, not the race. A young monkey is no
more likely to be transmuted into a man than an old one; nor is such a
metamorphosis at all more probable in the course of its foetal life.

The view we have now obtained of the specific differences between
distinct races of being at separate periods of their existence is
precisely what might have been anticipated from the law of gradual
development, which holds throughout the organic kingdoms. Between two
mature animals, these differences are perfectly obvious and well
marked. As we go a step back in their history, the distinction becomes a
little more obscure; two worms may resemble each other very closely,
though the two winged insects subsequently produced from them may be
very unlike. Receding still farther, some of these specific differences
may entirely disappear, the organs or parts which should exhibit them
being not yet devel