e of a
fish, a reptile and a bird. But, to this question, observation gives a
peremptory answer. It shows that up to a certain period in its
development the embryo of the bird is hardly distinguishable from that
of the reptile, and that the individual develops, throughout the
embryonic life in general, a series of transformations comparable to
those through which, according to the theory of evolution, one species
passes into another. A single cell, the result of the combination of two
cells, male and female, accomplishes this work by dividing. Every day,
before our eyes, the highest forms of life are springing from a very
elementary form. Experience, then, shows that the most complex has been
able to issue from the most simple by way of evolution. Now, has it
arisen so, as a matter of fact? Paleontology, in spite of the
insufficiency of its evidence, invites us to believe it has; for, where
it makes out the order of succession of species with any precision, this
order is just what considerations drawn from embryogeny and comparative
anatomy would lead any one to suppose, and each new paleontological
discovery brings transformism a new confirmation. Thus, the proof drawn
from mere observation is ever being strengthened, while, on the other
hand, experiment is removing the objections one by one. The recent
experiments of H. de Vries, for instance, by showing that important
variations can be produced suddenly and transmitted regularly, have
overthrown some of the greatest difficulties raised by the theory. They
have enabled us greatly to shorten the time biological evolution seems
to demand. They also render us less exacting toward paleontology. So
that, all things considered, the transformist hypothesis looks more and
more like a close approximation to the truth. It is not rigorously
demonstrable; but, failing the certainty of theoretical or experimental
demonstration, there is a probability which is continually growing, due
to evidence which, while coming short of direct proof, seems to point
persistently in its direction: such is the kind of probability that the
theory of transformism offers.

Let us admit, however, that transformism may be wrong. Let us suppose
that species are proved, by inference or by experiment, to have arisen
by a discontinuous process, of which to-day we have no idea. Would the
doctrine be affected in so far as it has a special interest or
importance for us? Classification would probably remain,