Leghorn cock.]

In connection with intermediates a more cogent objection to the Mendelian
view is the case of the first cross between two definite varieties
thenceforward breeding true. The case that will naturally occur to the
reader is that of the mulatto, which results from the cross between the
negro and the white. According to general opinion, these mulattos, of
intermediate pigmentation, continue to produce mulattos. Unfortunately this
interesting case has never been critically investigated, and the statement
that the mulatto breeds true rests almost entirely upon {130} information
that is general and often vague. It may be that the inheritance of skin
pigmentation in this instance is a genuine exception to the normal rule,
but at the same time it must not be forgotten that it may be one in which
several interacting factors are concerned, and that the pure white and the
pure black are the result of combinations which from their rarity are apt
to be overlooked. But until we are in possession of accurate information it
is impossible to pronounce definitely upon the nature of the inheritance in
this case.

[Illustration: FIG. 29.

Pedigree of a family which originated from a cross between a Hindu and a
European. Black signs denote individuals as dark as average Hindus. Plain
signs denote quite-fair members, while those with a dot in the centre are
intermediate.]

{131}

On the other hand, from the cross between the darkly pigmented Eastern
races and the white segregation seems to occur in subsequent generations.
Families are to be found in which one parent is a pure white, while the
other has arisen from the cross between the dark and light in the first or
some subsequent generation. Such families may contain children
indistinguishable from pure blonds as well as children of very dark and of
intermediate shades. As an example, I may give the following pedigree,
which was kindly communicated to me by an Anglo-Indian friend (Fig. 29).
The family had resided in England for several generations, so that in this
case there was no question of a further admixture of black. Most noticeable
is the family produced by a very dark lady who had married a white man.
Some of the children were intermediate in colour, but two were fair whites
and two were dark as dark Hindus. This sharp segregation or splitting out
of blacks and whites in addition to intermediates strongly suggests that
the nature of the inheritance is Mendelian,