The genetic and the operative evidence relating to secondary sexual charactersMorgan, Thomas Hunt
Science
The genetic and the operative evidence relating to secondary sexual characters
Morgan, Thomas Hunt
Genetics; Poultry; Sex (Biology)
_C._ (1) Sebright type. Very dark with much stippling. Some
penciling on back. Breast dark; neck like that of Sebright.
(2) Sebright type like (1), but not such clear yellow. Secondaries
and tail feathers and coverts stippled (with black tips).
(3) Yellow Sebright. Neck and breast yellow with black base and tip
to feathers. Cape, breast, and wings (except bow) penciled to
barred.
_C._ to _D._ (1) Pale yellow, breast spangled, back lightly
penciled, tail same. Secondaries yellow and little stippled. Upper
web of primaries stippled.
(2) Breast spangled, rest as in (1).
(3) Same as (2).
_L._ Dark Sebright. Back-feathers broadly laced and a little
penciled. Neck black with yellow centers to feathers and yellow
edges (reversed Sebright).
All of the preceding hens except A are in general Sebrights. The last
three are pale stippled Sebrights.
BACK-CROSS HEN-FEATHERED COCKS.
_A._ One cock like F₁ male, but rather paler on back.
_C._ Four cocks. Light Sebrights, but spangled, in general, instead
of laced. Feathers clear, not stippled.
_G._ One black.
_L._ Dark Sebright. Back and rump black. Feathers with narrow
center, not stippled.
_Q._ Dark Sebright nearer to hen C (1). Thoroughly stippled with
game tail. Neck and breast dark Sebright. Probably a new class
nearer to (C).
_R._ Two cocks. Pale yellow instead of reddish, and much less black
than are other yellows. No class of hens to match.[2]
In regard to color inheritance the preceding 19 birds are too few to add
anything of significance to the other results, except that they serve to
emphasize the dominance of the factors making for Sebright coloration.
The hen-feathered cocks confirm the other results as to the dominance of
the factor or factors in question.
There can be little doubt that some of these classes are complex. They
almost merge into each other and in one part of the body individuals
may grade off into one class, in other parts into other classes. An
almost continuous series of types might be arranged from black to pale
yellow.
The difficulty of matching the hen-feathered males to their genetic
mates is almost insuperable. In table 1 an attempt was made to put these
males with their respective females. The difficulty is, of course,
greater for the cock-feathered birds, even with the castration evidence
(that is too meager at present for the purpose), but a few of the males
may be placed with certainty, and the rest guessed at.
One bird appears to be a _hen-feathered_ game male resembling in many
respects the female game, but darker and redder. There is more shafting
on cape and wing-bow. The breast is unusually dark-salmon. The hackle is
darker than is the game female. Upper wing-coverts broadly laced with
black. (Plate 10, fig. 3.)
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