ful adaptations on the part of the plants; so that special
creationists must resort to the almost impious supposition that in these
cases the Deity has only carried out half his plan, in that while he
made an elaborate provision for these uniquely created species of
plants, which depended for its efficiency on the presence of quadrupeds,
he nevertheless neglected to place any quadrupeds on the islands where
he had placed the plants. Such one-sided attempts at adaptation surely
resolve the thesis of special creation to a _reductio ad absurdum_; and
hence the only reasonable interpretation of them is, that while the
seeds of allied or ancestral plants were able to float to the islands,
no quadrupeds were ever able over so great a distance to swim.

* * * * *

Although much more evidence might still be given under the head of
geographical distribution, I must now close with a brief summary of the
main points that have been adduced.

After certain preliminary considerations, I began by noticing that the
theory of evolution has a much more intelligible account to give than
has its rival of the facts of discontinuous distribution--the Alpine
flora, for instance, being allied to the Arctic, not because the same
species were separately created in both places, but because during the
glacial period these species extended all over Europe, and were left
behind on the Alps as the Arctic flora receded northwards--which was
sufficiently long ago to explain why some of the Alpine species are
unique, though closely allied to Arctic forms.

Next we saw that, although living things are always adapted to the
climates under which they live (since otherwise they could not live
there at all), it is equally true that, as a rule, besides the area on
which they do live, there are many other areas in different parts of the
globe where they might have lived equally well. Consequently we must
conclude that, if all species were separately created, many species were
severally created on only one among a number of areas where they might
equally well have thrived. Now, although this conclusion in itself may
not seem opposed to the theory of special creation, a most serious
difficulty is raised when it is taken in connexion with another fact of
an equally general kind. This is, that on every biological region we
encounter chains of allied species constituting allied genera, families,
and so on; while we scarcely ever me