and only at a late stage a form that has a resemblance to the ape;
until at last the definite human form emerges and closes the series of
transformations. These suggestive facts are, as I said, still almost
unknown to the general public--so completely unknown that, if one
casually mentions them, they are called in question or denied outright
as fairy-tales. Everybody knows that the butterfly emerges from the
pupa, and the pupa from a quite different thing called a larva, and
the larva from the butterfly's egg. But few besides medical men are
aware that MAN, in the course of his individual formation, passes
through a series of transformations which are not less surprising and
wonderful than the familiar metamorphoses of the butterfly.

The mere description of these remarkable changes through which man
passes during his embryonic life should arouse considerable interest.
But the mind will experience a far keener satisfaction when we trace
these curious facts to their causes, and when we learn to behold in
them natural phenomena which are of the highest importance throughout
the whole field of human knowledge. They throw light first of all on
the "natural history of creation," then on psychology, or "the science
of the soul," and through this on the whole of philosophy. And as the
general results of every branch of inquiry are summed up in
philosophy, all the sciences come in turn to be touched and influenced
more or less by the study of the evolution of man.

But when I say that I propose to present here the most important
features of these phenomena and trace them to their causes, I take the
term, and I interpret my task, in a very much wider sense than is
usual. The lectures which have been delivered on this subject in the
universities during the last half-century are almost exclusively
adapted to medical men. Certainly, the medical man has the greatest