wever, is less rigorous than the
other; it does not require the death of the less successful, but gives
to them fewer descendants. This struggle falls, moreover, at a time of
year when food is generally abundant, and perhaps the effect chiefly
produced would be the alteration of sexual characters, and the selection
of individual forms, no way related to their power of obtaining food, or
of defending themselves from their natural enemies, but of fighting one
with another. This natural struggle amongst the males may be compared in
effect, but in a less degree, to that produced by those agriculturalists
who pay less attention to the careful selection of all the young animals
which they breed and more to the occasional use of a choice male{237}.

{235} These two forms of sexual selection are given in _Origin_,
Ed. i. p. 87, vi. p. 107. The Guiana rock-thrush is given as an
example of bloodless competition.

{236} <Note in original.> Seals? Pennant about battles of seals.

{237} In the Linnean paper of July 1, 1858 the final word is
_mate_: but the context shows that it should be _male_; it is
moreover clearly so written in the MS.

_Differences between "Races" and "Species":--first, in their trueness or
variability._

Races{238} produced by these natural means of selection{239} we may
expect would differ in some respects from those produced by man. Man
selects chiefly by the eye, and is not able to perceive the course of
every vessel and nerve, or the form of the bones, or whether the
internal structure corresponds to the outside shape. He{240} is unable
to select shades of constitutional differences, and by the protection he
affords and his endeavours to keep his property alive, in whatever
country he lives, he checks, as much as lies in his power, the selecting
action of nature, which will, however, go on to a lesser degree with all
living things, even if their length of life is not determined by their
own powers of endurance. He has bad judgment, is capricious, he does
not, or his successors do not, wish to select for the same exact end for
hundreds of generations. He cannot always suit the selected form to the
properest conditions; nor does he keep those conditions uniform: he
selects that which is useful to him, not that best adapted to those
conditions in which each variety is placed by him: he selects a small
dog, but feeds it highly; he selects a long-backed dog, but does not