most markedly this peculiar quality or variation will be the
most likely to escape, those without it to perish. If a form varies
unfavorably, becomes for instance more conspicuous to its enemies,
it will almost certainly perish. Thus favorable variations tend to
increase and become more marked from generation to generation.

Now it has always been known that breeders could produce a race of
markedly peculiar form or characteristics by selecting the
individuals possessing this quality in the highest degree and
breeding only from these. The breeder depends upon heredity,
variation, and his selection of the individuals from which to breed.
Similarly in nature new species have arisen through heredity,
variation, and a selection according to the laws of nature of those
varying in conformity with their environment. And this Mr. Darwin
called natural, in contrast with the breeder's artificial,
"selection," arising from the "struggle for existence," and
resulting in what Mr. Spencer has called the "survival of the
fittest."

Let us take a single illustration. Many of the species of beetles on
oceanic islands have very rudimentary wings, or none at all, and yet
their nearest relatives are winged forms on some neighboring
continent. Mr. Darwin would explain the origin of these evidently
distinct wingless species as follows: They are descended from winged
ancestors blown or otherwise transported thither from the
neighboring continent. But beetles are slow and clumsy fliers, and
on these wind-swept islands those which flew most would be blown out
to sea and drowned. Those which flew the least, and these would
include the individuals with more poorly developed wings, would
survive. There would thus be a survival in every generation of a
larger proportion of those having the poorest wings, and destruction
of those whose wings were strong, or whose habits most active. We
have here a natural selection which must in time produce a species
with rudimentary or aborted wings, just as surely as a human
breeder, by artificial selection can produce such an animal as a pug
or a poodle. These, like sin, are a human device; nature should not
be held responsible for them.

But you may urge that the variation which would take place in a
single generation would be, as a rule, too slight to be of any
practical value to the animal, and could not be fostered by natural
selection until greatly enhanced by some other means. Let us think a
moment.