Again, of the one hundred eggs of an insect let us suppose that only sixty develop into the first larval, caterpillar, stage.  Of these sixty, the number of members of the species remaining constant, only two will survive.  The other fifty-eight die—­of starvation, parasites, or other enemies, or from inclement weather.  Now which two of all shall survive?  Those naturally best able to escape their enemies or to resist unfavorable influences; in a word, those best suited to their conditions, or, to use Mr. Darwin’s words, “conformed to their environment.”

Now if any individual has varied so as to possess some peculiarity which enables it even in slight degree to better escape its enemies or to resist unfavorable conditions, those of its descendants who inherit 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.