like 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
plant, from which it departs by morphological and physiological
variations suited to a more energized form of life; and the female may
be regarded as the animal norm from which the male departs by further
morphological variations. It is now well known that variations are
more frequent and marked in males than in females. Among the lower
forms, in which activity is more directly determined mechanically
by the stimuli of heat, light, and chemical attraction, and where
in general the food and light are evenly distributed through the
medium in which life exists, and where the limits of variation
are consequently small, the constitutional nutritive tendency of
the female manifests itself in size. Among many Cephalopoda and
Cirripedia, and among certain of the Articulata, the female is larger
than the male. Female spiders, bees, wasps, hornets, and butterflies
are larger than the males, and the difference is noticeable even in
the larval stage. So considerabl