ic descent from the drift period down
to the present, and allow time enough--if time is of any account--for
variation and natural selection to work out some appreciable results
in the way of divergence into races or even into so-called species.
Whatever might have been thought, when geological time was supposed
to be separated from the present era by a clear line, it is certain
that a gradual replacement of old forms by new ones is strongly
suggestive of some mode of origination which may still be operative.
When species, like individuals, were found to die out one by one, and
apparently to come in one by one, a theory for what Owen sonorously
calls "the continuous operation of the ordained becoming of living
things" could not be far off.

That all such theories should take the form of a derivation of the
new from the old seems to be inevitable, perhaps from our inability
to conceive of any other line of secondary causes, in this
connection. Owen himself is apparently in travail with some
transmutation theory of his own conceiving, which may yet see the
light, although Darwin's came first to the birth. Different as the
two theories will probably be in particulars, they cannot fail to
exhibit that fundamental resemblance in this respect which betokens a
community of origin, a common foundation on the general facts and the
obvious suggestions of modern science. Indeed,--to turn the point of
a taking simile directed against Darwin,--the difference between the
Darwinian and the Owenian hypotheses may, after all, be only that
between homoeopathic and heroic doses of the same drug.

If theories of derivation could only stop here, content with
explaining the diversification and succession of species between the
tertiary period and the present time, through natural agencies or
secondary causes still in operation, we fancy they would not be
generally or violently objected to by the _savans_ of the present
day. But it is hard, if not impossible, to find a stopping-place.
Some of the facts or accepted conclusions already referred to, and
several others, of a more general character, which must be taken into
the account, impel the theory onward with accumulated force. _Vires_
(not to say _virus) acquirit eundo_. The theory hitches on
wonderfully well to Lyell's uniformitarian theory in geology,--that
the thing that has been is the thing that is and shall be,--that the
natural operations now going on will account for all geological