The Descent of Man

of the males. Nevertheless we have a near approach
to close sexual similarity or dissimilarity
throughout several groups: and this, from
what has just been said of the fluctuating nature
of inheritance, is a somewhat surprising circumstance.
But that the same laws should largely
prevail with allied animals is not surprising.
The domestic fowl has produced a great
number of breeds and sub-breeds, and in these
the sexes generally differ in plumage; so that it
has been noticed as an unusual circumstance
when in certain sub-breeds they resemble each
other. On the other hand, the domestic pigeon
has likewise produced a vast number of distinct
breeds and sub-breeds, and in these, with rare
exceptions, the two sexes are identically alike.
Therefore if other species of Gallus and Columba
were domesticated and varied, it would not
be rash to predict that similar rules of sexual
similarity and dissimilarity, depending on the
form of transmission, would hold good in both