90 
NATUPvAL SELECTION. 
Chap. IV. 
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 peculi- 
a.rities 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, 
(fee.), 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, 
liad the tuft appeared under domestication, it would 
iiave been called a monstrosity. 
Illustrations of the action of Natural Selection .—In 
order to make it clear how, as I believe, natural selec¬ 
tion 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 
irom 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 
liave 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 grey¬ 
hounds by careful and methodical selection, or by that 
unconscious selection which results from each man trying 
