ill
persist, so long as none of the varieties which it throws off are better
adapted than itself.

On the other hand, as soon as it varies in a useful way, i.e. when the
variation is such as to adapt it more perfectly to its conditions, the
fresh variety will tend to supplant the former.

So far from a gradual progress towards perfection forming any necessary
part of the Darwinian creed, it appears to us that it is perfectly
consistent with indefinite persistence in one estate, or with a gradual
retrogression. Suppose, for example, a return of the glacial epoch and a
spread of polar climatal conditions over the whole globe. The operation
of natural selection under these circumstances would tend, on the whole,
to the weeding out of the higher organisms and the cherishing of the
lower forms of life. Cryptogamic vegetation would have the advantage
over Phanerogamic; Hydrozoa over Corals; Crustacea over Insecta, and
Amphipoda and Isopoda over the higher Crustacea; Cetaceans and Seals
over the Primates; the civilization of the Esquimaux over that of the
European.

"5. Pelzeln has also objected that if the later organisms have proceeded
from the earlier, the whole developmental series, from the simplest to
the highest, could not now exist; in such a case the simpler organisms
must have disappeared."

To this Professor Kolliker replies, with perfect justice, that the
conclusion drawn by Pelzeln does not really follow from Darwin's
premisses, and that, if we take the facts of Palaeontology as they
stand, they rather support than oppose Darwin's theory.

"6. Great weight must be attached to the objection brought forward by
Huxley, otherwise a warm supporter of Darwin's hypothesis, that we know
of no varieties which are sterile with one another, as is the rule among
sharply distinguished animal forms.

"If Darwin is right, it must be demonstrated that forms may be produced
by selection, which, like the present sharply distinguished animal
forms, are infertile, when coupled with one another, and this has not
been done."

The weight of this objection is obvious; but our ignorance of the
conditions of fertility and sterility, the want of carefully conducted
experiments extending over long series of years, and the strange
anomalies presented by the results of the cross-fertilization of many
plants, should all, as Mr. Darwin has urged, be taken into account in
considering it.

The seventh objection is that we have already d