fifteen times the distance from these
islands that they are from one another, emigration to them from the
continent is of much more rare occurrence than emigration from one
island to another; and therefore, as more time for variation is thus
allowed, while the differences between the inhabitants of island and
island are only specific, the differences between the inhabitants of the
islands as a group and the inhabitants of the American continent are
very often generic. I may mention, in passing, that it was upon
discovering these relations in the case of the Galapagos Archipelago,
and pondering upon them as "marvellous facts," that Mr. Darwin was first
led to entertain the idea that the doctrine of descent might be the
grand truth for which the science of the nineteenth century was waiting.

The evidence from oceanic islands, however, is not yet exhausted; for
in no part of the world is there an oceanic island more than a certain
distance from a mainland in which any species of the large class of
frogs, toads, and newts is to be found. Why is this? Simply because
these animals, and their spawn, are quickly killed by contact with
sea-water; and therefore frogs, toads, and newts have never been able to
reach oceanic islands in a living state. Similarly in all oceanic
islands situated more than three hundred miles from land, no species of
the whole class of mammals is to be found, excepting species of the only
order of mammals which can fly, viz., bats. And, as if to make the case
still stronger, these forlornly created species of bats sometimes differ
from all other bats in the world. But can we, as reasonable men, suppose
that the Deity has chosen, without any apparent reason, never to create
any frog, toad, newt, or mammal on any oceanic island, save only such
species as are able to fly? Or, if we go so far as to say,--"There may
have been some hidden reason why batrachians and quadrupeds should not
have been created on oceanic islands," I will adduce another very
remarkable fact, viz., that on some of these islands there occur species
of plants, the seeds of which are provided with numerous hooks adapted
to catch the hair of moving quadrupeds, and so to become disseminated.
But, as we have just seen, there are no quadrupeds in these islands to
meet this case of adaptation; so that special creationists must resort
to the almost impious hypothesis, that in these cases the Deity only
carried out half His plan, in that whil