n in the rock-pigeon, as was the stomach.
So that two black barbs, a red spot, and a white fantail, as the four
purely-bred grandparents, produced a bird of the same general blue colour,
together with every characteristic mark, as in the wild _Columba livia_.

With respect to crossed breeds frequently producing blue birds chequered
with black, and resembling in all respects both the dovecot-pigeon and the
chequered wild variety of the rock-pigeon, the statement before referred to
by MM. Boitard and Corbie would almost suffice; but I will give three
instances of the appearance of such birds from crosses in which one alone
of the parents or great-grandparents was blue, but not chequered. I crossed
a male blue turbit with a snow-white trumpeter, and the following year with
a dark, leaden-brown, short-faced tumbler; the offspring from the first
cross were as perfectly chequered as any dovecot-pigeon; and from the
second, so much so as to be nearly as black as the most darkly chequered
rock-pigeon from Madeira. Another bird, whose great-grandparents were a
white trumpeter, a white fantail, a white red-spot, a red runt, and a blue
pouter, was slaty-blue and chequered exactly like a dovecot-pigeon. I may
here {201} add a remark made to me by Mr. Wicking, who has had more
experience than any other person in England in breeding pigeons of various
colours: namely, that when a blue, or a blue and chequered bird, having
black wing-bars, once appears in any race and is allowed to breed, these
characters are so strongly transmitted that it is extremely difficult to
eradicate them.

What, then, are we to conclude from this tendency in all the chief domestic
races, both when purely bred and more especially when intercrossed, to
produce offspring of a blue colour, with the same characteristic marks,
varying in the same manner, as in _Columba livia_? If we admit that these
races have all descended from _C. livia_, no breeder will doubt that the
occasional appearance of blue birds thus characterised is accounted for on
the well-known principle of "throwing back" or reversion. Why crossing
should give so strong a tendency to reversion, we do not with certainty
know; but abundant evidence of this fact will be given in the following
chapters. It is probable that I might have bred even for a century pure
black barbs, spots, nuns, white fantails, trumpeters, &c., without
obtaining a single blue or barred bird; yet by crossing these breeds I
re