characters proper to one sex may suddenly appear in the other sex; as
in those sub-breeds of the fowl in which the hens acquire spurs whilst
young; or, as in certain Polish sub-breeds, in which the females, as
there is reason to believe, originally acquired a crest, and
subsequently transferred it to the males. All these cases are
intelligible on the hypothesis of pangenesis; for they depend on the
gemmules of certain parts, although present in both sexes, becoming,
through the influence of domestication, either dormant or developed in
either sex.
There is one difficult question which it will be convenient to defer to
a future chapter; namely, whether a character at first developed in
both sexes, could through selection be limited in its development to
one sex alone. If, for instance, a breeder observed that some of his
pigeons (of which the characters are usually transferred in an equal
degree to both sexes) varied into pale blue, could he by long-continued
selection make a breed, in which the males alone should be of this
tint, whilst the females remained unchanged? I will here only say, that
this, though perhaps not impossible, would be extremely difficult; for
the natural result of breeding from the pale-blue males would be to
change the whole stock of both sexes to this tint. If, however,
variations of the desired tint appeared, which were from the first
limited in their development to the male sex, there would not be the
least difficulty in making a breed with the two sexes of a different
colour, as indeed has been effected with a Belgian breed, in which the
males alone are streaked with black. In a similar manner, if any
variation appeared in a female pigeon, which was from the first
sexually limited in its development to the females, it would be easy to
make a breed with the females alone thus characterised; but if the
variation was not thus originally limited, the process would be
extremely difficult, perhaps impossible. (37. Since the publication of
the first edition of this work, it has been highly satisfactory to me
to find the following remarks (the Field, Sept. 1872) from so
experienced a breeder as Mr. Tegetmeier. After describing some curious
cases in pigeons, of the transmission of colour by one sex alone, and
the formation of a sub-breed with this character, he says: It is a
singular circumstance that Mr. Darwin should have suggested the
possibility of modifying the sexual colours of birds by a course of
artificial selection. When he did so, he was in ignorance of these
facts that I have related; but it is remarkable how very closely he
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