Actually I found, as Darwin (1876) did, that the chicks of this first hybrid generation were all wholly black. In this respect they differed markedly from the chicks of the Silkie, which are pure white, and also from the chicks of the Minorca, which are prevailingly black, but have white belly and outer primaries. The white in the young chicks of Minorcas is extremely variable in amount, but never wholly absent; in time, as the bird grows older, it is replaced by black, so that the adult male and female Minorcas have a wholly black plumage. The reason for the precocious development of black pigment over the belly and primaries of the hybrid chicks is probably the presence of an extension factor (_cf._ Castle, 1909) derived from the Silkie. Certain it is that the ordinary Jungle pattern develops pigment on the belly and on the wings, as well as on other parts of the plumage. The hybrid chicks may be said to have the extended pigmentation dominant over interrupted pigmentation. In the adult hybrids a difference appears between the coloration of the male and female, even as Darwin pointed out. For the latter retains its uniform blackness, while the former gains red on the wing-bar, and saddle and hackle lacing (plate 4). Now, since all the factors present in the Minorca, and none others, are present in the hybrids, why should the male hybrids show red, and why should the males show red and not the females? The answer to the first question is, I think, clear. While the Jungle pattern of black and red is completely obscured by the undiluted _N_ factor of the Minorca, it is only incompletely covered by the diluted, heterozygous _N_ factor of the hybrid. Hence the red appears in greatly reduced amount, as compared with the Jungle-fowl. In the female Jungle-fowl there is little red and consequently none shows in the female hybrid. Thus the difference in the sexes of the hybrids corresponds to the sexual dimorphism of the Jungle-fowl; but the hybrids are, as indicated, very unlike the Jungle-fowl in coloration (_cf._ plates 1 and 2). Since segregation takes place in the gametes of these heterozygotes, 4 kinds of gametes are possible, namely, _CJN_, _CJn_, _cJN_, _cJn_. On mating heterozygotes together, zygotes of 16 types will be formed, as in table 57. TABLE 57.--_Zygotes in F2 of Silkie × Minorca hybrids and their corresponding somatic colors._ +------------+-----------+-----------+-----------+ | C2J2N2 N | C2J2Nn N | CcJ2N2 N | CcJ2Nn N | | C2J2Nn N | C2J2n2 G | CcJ2Nn N | CcJ2n2 G | | CcJ2N2 N | CcJ2Nn N | c2J2N2 W | c2J2Nn W | | CcJ2Nn N | CcJ2n2 G | c2J2Nn W | c2J2n2 W | +------------+-----------+-----------+-----------+ TABLE 58.