273,
and vol. cxcv, p. 113; _Proceedings of the Royal Society_, vol. lxvi, p.
28; _Grammar of Science_, second edition, 1900, pp. 425 _et seq._;
_Biometrika_, November, 1903. The last-named periodical also contains a
study on "Assortative Mating in Man," bringing forward evidence to show
that, apart from environmental influence, "length of life is a character
which is subject to selection;" that is to say, the long-lived tend to
marry the long-lived, and the short-lived to marry the short-lived.

[182] For a summary of the evidence on this point see Havelock Ellis, _Man
and Woman_, fourth edition, 1904, pp. 256-264.

[183] "The Comparative Abilities of the Fair and the Dark," _Monthly
Review_, August, 1901.

[184] The fact that even in Europe the abhorrence to incest is not always
strongly felt is brought out by Bloch, _Beitraege zur AEtiologie der
Psychopathia Sexualis_, Teil II, pp. 263 et seq.

[185] Westermarck, _History of Marriage_, Chapters XIV and XV.

[186] Crawley (_The Mystic Rose_, p. 446) has pointed out that it is not
legitimate to assume the possibility of an "instinct" of this character;
instinct has "nothing in its character but a response of function to
environment."

[187] Fromentin, in his largely autobiographic novel _Dominique_, makes
Olivier say: "Julie is my cousin, which is perhaps a reason why she should
please me less than anyone else. I have always known her. We have, as it
were, slept in the same cradle. There may be people who would be attracted
by this almost fraternal relationship. To me the very idea of marrying
someone whom I knew as a baby is as absurd as that of coupling two dolls."

[188] It may well be, as Crawley argues (_The Mystic Rose_, Chapter XVII),
that sexual taboo plays some part among primitive people in preventing
incestuous union, as, undoubtedly, training and moral ideas do among
civilized peoples.

[189] The remarks of the Marquis de Brisay, an authority on doves, as
communicated to Giard (_L'Intermediare des Biologistes_, November 20,
1897), are of much interest on this point, since they correspond to what
we find in the human species: "Two birds from the same nest rarely couple.
Birds coming from the same nest behave as though they regarded coupling as
prohibited, or, rather, they know each other too well, and seem to be
ignorant of their difference in sex, remaining unaffected in their
relations by the changes which make them adults." Westermarck (op. cit.,