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.