ially by
alienists, as leading to sexual unions of parity, notwithstanding the
belief in the generally superior attraction of disparity. It has often
been pointed out that the neuropathic, the insane and criminal,
"degenerates" of all kinds, show a notable tendency to marry each other.
This tendency has not, however, been investigated with any precision.[177]

The first attempt on a statistical basis to ascertain what degree of
parity or disparity is actually attained by sexual selection was made by
Alphonse de Candolle.[178] Obtaining his facts from Switzerland, North
Germany, and Belgium, he came to the conclusion that marriages are most
commonly contracted between persons with different eye-colors, except in
the case of brown-eyed women, who (as Schopenhauer stated, and as is seen
in the English data of the sexual ideal I have brought forward) are found
more attractive than others.

The first series of serious observations tending to confirm the result
reached by the genius of Leonardo da Vinci and to show that sexual
selection results in the pairing of like rather than of unlike persons was
made by Hermann Fol, the embryologist.[179] He set out with the popular
notion that married people end by resembling each other, but when at Nice,
which is visited by many young married couples on their honeymoons, he was
struck by the resemblances already existing immediately after marriage. In
order to test the matter he obtained the photographs of 251 young and old
married couples not personally known to him. The results were as follows:

RESEMBLANCES NONRESEMBLANCES
COUPLES. (PERCENTAGE). (PERCENTAGE). TOTAL.

Young.............. 132, about 66,66 66, about 33.33 198
Old ................ 38, about 71.70 15, about 28.30 53

He concluded that in the immense majority of marriages of inclination the
contracting parties are attracted by similarities, and not by
dissimilarities, and that, consequently, the resemblances between aged
married couples are not acquired during conjugal life. Although Fol's
results were not obtained by good methods, and do not cover definite
points like stature and eye-color, they represented the conclusions of a
highly skilled and acute observer and have since been amply confirmed.

Galton could not find that the average results from a fairly large number
of cases indicated that stature, eye-color, or other personal
characteristics notably influence