s, _Sensations Internes_, ch. v, "Besoins Sexuels," 1889. It
may be noted that many years earlier Burdach (in his _Physiologie als
Erfahrungswissenschaft_, 1826) had recognized that the activity of the
male favored procreation, and that mental and physical excitement seemed
to have the same effect in the female also.

[25] It is scarcely necessary to point out that this is too extreme a
position. As J.G. Millais remarks of ducks (_Natural History of British
Ducks_, p. 45), in courtship "success in winning the admiration of the
female is rather a matter of persistent and active attention than physical
force," though the males occasionally fight over the female. The ruff
(_Machetes pugnax_) is a pugnacious bird, as his name indicates. Yet, the
reeve, the female of this species, is, as E. Selous shows ("Sexual
Selection in Birds," _Zooelogist_, Feb. and May, 1907), completely mistress
of the situation. "She seems the plain and unconcerned little mistress of
a numerous and handsome seraglio, each member of which, however he flounce
and bounce, can only wait to be chosen." Any fighting among the males is
only incidental and is not a factor in selection. Moreover, as R. Mueller
points out (loc. cit., p. 290), fighting would not usually attain the end
desired, for if the males expend their time and strength in a serious
combat they merely afford a third less pugnacious male a better
opportunity of running off with the prize.

[26] L. Tillier, _L'Instinct Sexuel_, 1889, pp. 74, 118, 119, 124 et seq.,
289.

[27] K. Groos, _Die Spiele der Thiere_, 1896; _Die Spiele der Menschen_,
1899; both are translated into English.

[28] Prof. H.E. Ziegler, in a private letter to Professor Groos, _Spiele
der Thiere_, p. 202.

[29] _Die Spiele der Thiere_, p. 244. This had been briefly pointed out by
earlier writers. Thus, Haeckel (_Gen. Morph._, ii, p. 244) remarked that
fighting for females is a special or modified kind of struggle for
existence, and that it acts on both sexes.

[30] It may be added that in the human species, as Bray remarks ("Le Beau
dans la Nature," _Revue Philosophique_, October, 1901, p. 403), "the hymen
would seem to tend to the same end, as if nature had wished to reinforce
by a natural obstacle the moral restraint of modesty, so that only the
vigorous male could insure his reproduction." There can be no doubt that
among many animals pairing is delayed so far as possible until maturity is
reached. "It is a strict