their transmission.
The Spanish fowl offers a more curious case; the male has an immense
comb, but some of the successive variations, by the accumulation of
which it was acquired, appear to have been transferred to the female;
for she has a comb many times larger than that of the females of the
parent species. But the comb of the female differs in one respect from
that of the male, for it is apt to lop over; and within a recent period
it has been ordered by the fancy that this should always be the case,
and success has quickly followed the order. Now the lopping of the comb
must be sexually limited in its transmission, otherwise it would
prevent the comb of the male from being perfectly upright, which would
be abhorrent to every fancier. On the other hand, the uprightness of
the comb in the male must likewise be a sexually-limited character,
otherwise it would prevent the comb of the female from lopping over.
From the foregoing illustrations, we see that even with almost
unlimited time at command, it would be an extremely difficult and
complex, perhaps an impossible process, to change one form of
transmission into the other through selection. Therefore, without
distinct evidence in each case, I am unwilling to admit that this has
been effected in natural species. On the other hand, by means of
successive variations, which were from the first
sexually limited in their transmission, there would not be the least
difficulty in rendering a male bird widely different in colour or in
any other character from the female; the latter being left unaltered,
or slightly altered, or specially modified for the sake of protection.
As bright colours are of service to the males in their rivalry with
other males, such colours would be selected whether or not they were
transmitted exclusively to the same sex. Consequently the females might
be expected often to partake of the brightness of the males to a
greater or less degree; and this occurs with a host of species. If all
the successive variations were transmitted equally to both sexes, the
females would be indistinguishable from the males; and this likewise
occurs with many birds. If, however, dull colours were of high
importance for the safety of the female during incubation, as with many
ground birds, the females which varied in brightness, or which received
through inheritance from the males any marked accession of brightness,
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