ral Selection._

In order to make my argument intelligible, it is necessary for me to
explain very briefly the theory of "Natural Selection" promulgated by
Mr. Darwin, and the power which it possesses of modifying the forms of
animals and plants. The grand feature in the multiplication of organic
life is, that close general resemblance is combined with more or less
individual variation. The child resembles its parents or ancestors more
or less closely in all its peculiarities, deformities, or beauties; it
resembles them in general more than it does any other individuals; yet
children of the same parents are not all alike, and it often happens
that they differ very considerably from their parents and from each
other. This is equally true, of man, of all animals, and of all plants.
Moreover, it is found that individuals do not differ from their parents
in certain particulars only, while in all others they are exact
duplicates of them. They differ from them and from each other, in every
particular: in form, in size, in colour; in the structure of internal as
well as of external organs; in those subtle peculiarities which produce
differences of constitution, as well as in those still more subtle ones
which lead to modifications of mind and character. In other words, in
every possible way, in every organ and in every function, individuals of
the same stock vary.

Now, health, strength, and long life, are the results of a harmony
between the individual and the universe that surrounds it. Let us
suppose that at any given moment this harmony is perfect. A certain
animal is exactly fitted to secure its prey, to escape from its enemies,
to resist the inclemencies of the seasons, and to rear a numerous and
healthy offspring. But a change now takes place. A series of cold
winters, for instance, come on, making food scarce, and bringing an
immigration of some other animals to compete with the former inhabitants
of the district. The new immigrant is swift of foot, and surpasses its
rivals in the pursuit of game; the winter nights are colder, and require
a thicker fur as a protection, and more nourishing food to keep up the
heat of the system. Our supposed perfect animal is no longer in harmony
with its universe; it is in danger of dying of cold or of starvation.
But the animal varies in its offspring. Some of these are swifter than
others--they still manage to catch food enough; some are hardier and
more thickly furred--they manage