alike prejudicial.

If this is true, and if heightened nutrition yields an increased
proportion of females, we ought to find that breeding-out is favorable
to the production of females, and breeding-in to the production of
males; and a considerable body of evidence in favor of this assumption
exists.[19]

Observations of above 4,000 cases show that, among horses, the
more the parent animals differ in color, the more the female
foals outnumber the male. Similarly, in-and-in-bred cattle give
an excessively large number of bull calves. Liaisons produce an
abnormally large proportion of females;[20] incestuous unions,
of males.[21] Among the Jews, who frequently marry cousins, the
percentage of male births is very high.

According to Mr. Jacobs' comprehensive manuscript collection
of Jewish statistics ... the average proportion of male and
female Jewish births registered in various countries is 114.5
males to 100 females, whilst the average proportion among the
non-Jewish population of the corresponding countries is 105.25
males to 100 females.... His collection includes details
of 118 mixed marriages; of these 28 are sterile, and in the
remainder there are 145 female children and 122 male--that is,
118.82 females to 100 males.[22]

The testimony is also tolerably full that among _metis_ and among
exogamous peoples the female birth-rate is often excessively high.[23]

Viewed with reference to activity, the animal is an advance on the