The Descent of Man

on the principle of correlation the feathers over
the whole body are often coloured in the same
manner. We are thus enabled without much
trouble to rear breeds with their plumage marked
almost as symmetrically as in natural species.
In laced and spangled fowls the coloured
margins of the feathers are abruptly defined;
but in a mongrel raised by me from a black
Spanish cock glossed with green, and a white
game-hen, all the feathers were greenish-black,
excepting towards their extremities, which were
yellowish-white; but between the white extremities
and the black bases, there was on each
feather a symmetrical, curved zone of darkbrown.
In some instances the shaft of the feather
determines the distribution of the tints; thus
with the body-feathers of a mongrel from the
same black Spanish cock and a silver-spangled
Polish hen, the shaft, together with a narrow
space on each side, was greenish-black, and this
was surrounded by a regular zone of darkbrown,
edged with brownish-white. In these