, some slight
advantage over other {90} males, in their weapons, means of defence, or
charms; and have transmitted these advantages to their male offspring. Yet,
I would not wish to attribute all such sexual differences to this agency:
for we see peculiarities arising and becoming attached to the male sex in
our domestic animals (as the wattle in male carriers, horn-like
protuberances in the cocks of certain fowls, &c.), which we cannot believe
to be either useful to the males in battle, or attractive to the females.
We see analogous cases under nature, for instance, the tuft of hair on the
breast of the turkey-cock, which can hardly be either useful or ornamental
to this bird;--indeed, had the tuft appeared under domestication, it would
have been called a monstrosity.

_Illustrations of the action of Natural Selection._--In order to make it
clear how, as I believe, natural selection acts, I must beg permission to
give one or two imaginary illustrations. Let us take the case of a wolf,
which preys on various animals, securing some by craft, some by strength,
and some by fleetness; and let us suppose that the fleetest prey, a deer
for instance, had from any change in the country increased in numbers, or
that other prey had decreased in numbers, during that season of the year
when the wolf is hardest pressed for food. I can under such circumstances
see no reason to doubt that the swiftest and slimmest wolves would have the
best chance of surviving, and so be preserved or selected,--provided always
that they retained strength to master their prey at this or at some other
period of the year, when they might be compelled to prey on other animals.
I can see no more reason to doubt this, than that man can improve the
fleetness of his greyhounds by careful and methodical selection, or by that
unconscious selection which results from each man trying {91} to keep the
best dogs without any thought of modifying the breed.

Even without any change in the proportional numbers of the animals on which
our wolf preyed, a cub might be born with an innate tendency to pursue
certain kinds of prey. Nor can this be thought very improbable; for we
often observe great differences in the natural tendencies of our domestic
animals; one cat, for instance, taking to catch rats, another mice; one
cat, according to Mr. St. John, bringing home winged game, another hares or
rabbits, and another hunting on marshy ground and almost nightly catching