much to disgust at the aspect of what looks like an insulting
caricature, as to the awakening of a sudden and profound mistrust of
time-honoured theories and strongly-rooted prejudices regarding his own
position in nature, and his relations to the under-world of life; while
that which remains a dim suspicion for the unthinking, becomes a vast
argument, fraught with the deepest consequences, for all who are
acquainted with the recent progress of the anatomical and physiological
sciences.

I now propose briefly to unfold that argument, and to set forth, in a
form intelligible to those who possess no special acquaintance with
anatomical science, the chief facts upon which all conclusions
respecting the nature and the extent of the bonds which connect man with
the brute world must be based: I shall then indicate the one immediate
conclusion which, in my judgment, is justified by those facts, and I
shall finally discuss the bearing of that conclusion upon the
hypotheses which have been entertained respecting the Origin of Man.

The facts to which I would first direct the reader's attention, though
ignored by many of the professed instructors of the public mind, are
easy of demonstration and are universally agreed to by men of science;
while their significance is so great, that whoso has duly pondered over
them will, I think, find little to startle him in the other revelations
of Biology. I refer to those facts which have been made known by the
study of Development.

It is a truth of very wide, if not of universal, application, that every
living creature commences its existence under a form different from,
and simpler than, that which it eventually attains.