WINGLESSNESS.
The entire absence of appendages is a rare monstrosity, few cases
having been cited even for man. In my experience with poultry, out
of about 14,000 birds I have obtained one that had no wing on one
side of the body, but this unfortunately died before being bred from.
A second bird was given to me by a fancier. The bird was an Indian
Game, a vigorous cock, which was handicapped by his abnormality in
two ways. First, whenever he fell upon his side or back he was unable
to get upon his feet without aid. On several occasions he evidently
had spent hours upon the ground before he was discovered and picked
up. The wings are thus clearly most important to the fowl in enabling
it to regain its feet after having become prone. Secondly, he was
unable to tread a hen, since this act requires the use of wings as
balancers. He was, however, able to copulate with small birds without
leaving the ground. Thus in two respects his abnormality would have
proved fatal in nature. First, because of the personal risk, the
greater since a prone bird must fall an easy prey to predaceous
enemies; and secondly, because of the risk to his germ-plasm. Little
wonder, then, that this abnormality should not be known among wild
ground-birds.
Mated to 6 hens this wingless cock produced 130 chicks in 1907, of
which all had two wings. The following year he was mated to his
daughters, but died without leaving offspring. So I used a son of his
to mate with his own sisters and half-sisters. The progeny in this F2
generation consisted of 223 chicks, all of which had two wings. Thus,
no trace of winglessness appeared in any of the descendants of the
wingless cock.
The explanation of this case is not very certain, in view of the
limited data. It seems to resemble the behavior of No. 117, the
rumpless cock. And following the interpretation given in his case I
would conclude that winglessness is dominant to the normal condition,
that the original wingless cock was a heterozygote, and that the
dominance of winglessness was imperfect in the first generation. On
this hypothesis his son may well have been a pure recessive, and
then all of his descendants, in turn, would be either recessives
or heterozygotes (with imperfect dominance). It is, on the other
hand, possible that the wingless cock was a pure dominant, but that
the potency of the inhibitor was so slight as not to appear in the
heterozygotes or even in extracted dominants.