and space with
preexisting closely allied species." Not, however, that this is proved
even of existing species as a matter of general fact. It is obviously
impossible to _prove_ anything of the kind. But we must concede that the
known facts strongly suggest such an inference. And since species are
only congeries of individuals, and every individual came into existence
in consequence of preexisting individuals of the same sort, so leading
up to the individuals with which the species began, and since the only
material sequence we know of among plants and animals is that from
parent to progeny, the presumption becomes exceedingly strong that
the connection of the incoming with the preexisting species is a
genealogical one.

Here, however, all depends upon the probability that Mr. Wallace's
inference is really true. Certainly it is not yet generally accepted;
but a strong current is setting towards its acceptance.

So long as universal cataclysms were in vogue, and all life upon the
earth was thought to have been suddenly destroyed and renewed many times
in succession, such a view could not be thought of. So the equivalent
view maintained by Agassiz, and formerly, we believe, by D'Orbigny,
that, irrespectively of general and sudden catastrophes, or any known
adequate physical cause, there has been a total depopulation at the
close of each geological period or formation, say forty or fifty times,
or more, followed by as many independent great acts of creation, at
which alone have species been originated, and at each of which a
vegetable and an animal kingdom were produced entire and complete,
full-fledged, as flourishing, as wide-spread and populous, as varied and
mutually adapted from the beginning as ever afterwards,--such a view, of
course, supersedes all material connection between successive species,
and removes even the association and geographical range of species
entirely out of the domain of physical causes and of natural science.
This is the extreme opposite of Wallace's and Darwin's view, and is
quite as hypothetical. The nearly universal opinion, if we rightly
gather it, manifestly is, that the replacement of the species of
successive formations was not complete and simultaneous, but partial
and successive; and that along the course of each epoch some species
probably were introduced, and some, doubtless, became extinct. If all
since the tertiary belongs to our present epoch, this is certainly true
of it: if to