ning the folly of any
indiscriminate endowment of procreation.

[461] On the scientific side, in addition to the fruitful methods of
statistical biometrics, which have already been mentioned, much promise
attaches to work along the lines initiated by Mendel; see W. Bateson,
_Mendel's Principles of Heredity_, 1909; also, W.H. Lock, _Recent Progress
in the Study of Variation, Heredity, and Evolution_, and R.C. Punnett,
_Mendelism_, 1907 (American edition, with interesting preface by Gaylord
Wilshire, from the Socialistic point of view, 1909).

[462] The study of the right conditions for procreation is very ancient.
In modern times we find that even the very first French medical book in
the vulgar tongue, the _Regime du Corps_, written by Alebrand of Florence
(who was physician to the King of France), in 1256, is largely devoted to
this matter, concerning which it gives much sound advice. See J.B.
Soalhat, _Les Idees de Maistre Alebrand de Florence sur la Puericulture_,
These de Paris, 1908.

[463] Hesiod, _Works and Days_, II, 690-700.

[464] This has long been the accepted opinion of medical authorities, as
may be judged by the statements brought together two centuries ago by
Schurig, _Parthenologia_, pp. 22-25.

[465] The statement that, on the average, the best age for procreation in
men is before, rather than after, forty, by no means assumes the existence
of any "critical" age in men analogous to the menopause in women. This is
sometimes asserted, but there is no agreement in regard to it. Restif de
la Bretonne (_Monsieur Nicolas_, vol. x, p. 176) said that at the age of
forty delicacy of sentiment begins to go. Fuerbringer believes (Senator and
Kaminer, _Health and Disease in Relation to Marriage_, vol. i, p. 222)
that there is a decisive turn in a man's life in the sixth decade, or the
middle of the fifth, when desire and potency diminish. J.F. Sutherland
also states (_Comptes-rendus Congres International de Medecine_, 1900,
Section de Psychiatrie, p. 471) that there is, in men, about the
fifty-fifth year, a change analogous to the menopause in women, but only
in a certain proportion of men. It would appear that in most men the
decline of sexual feeling and potency is very gradual, and at first
manifests itself in increased power of control.

[466] See, in vol. i, the study of "The Phenomena of Sexual Periodicity."

[467] Among animals, also, spring litters are often said to be the best.

[468] Bossi's resu