As we have already seen, the gametic formula of the White Leghorn is _CJNWx_ and that of the Minorca is _CJNwx_, so that the F1 generation has the zygotic formula _C2J2N2Wwx2_ or, more simply, _C2J2N2Ww_. These heterozygotes are white because of the graying factor, but, as this factor is diluted, some black shows, particularly in the females. In F2, on account of there being only 1 heterozygous factor, only 3 kinds of zygotes are formed, _C2J2N2W2_, _C2J2N2Ww_, and _C2J2N2w2_, in the proportions 1: 2: 1. Since not only offspring homozygous in _W_, but also all male heterozygotes, are white and many female heterozygotes are late in revealing any pigment, it is necessary to consider together individuals homozygous and heterozygous in _W_. Consequently we may expect 75 per cent of the offspring to show white or white-black-speckled plumage, and 25 per cent black or black and white like the young Minorca. Actually, in 154 offspring (pen 633) I obtained 116 white + white-black + blue, and 38 black with more or less white and including 4 barred, of which more later. Expectation is 115.5 and 38.5, respectively. In another experiment I crossed the F1 hybrids on a pure White Leghorn and got 41 offspring, all white except 1 that showed some black specks. All results thus accord with hypothesis. 5. WHITE LEGHORN × BUFF COCHIN. (Plate 9.) These two races afford the gametic formulæ _CJNWx_ and _CjnwX_, respectively. The F1 hybrids consequently have the zygotic formula _C2JjNnWwXx_. Such hybrids are heterozygous in all factors except _C_. Such complex heterozygotism, combined with the well-known sex differences in color of heterozygotes, leads to a very great diversity of the offspring. As a matter of fact I found, as Hurst did, that the young were sometimes quite white, sometimes white and buff, and sometimes showed also a little black. Since there are 4 heterozygous characters, there are 256 possible combinations of them, which reduce to 81 different kinds of combinations. Owing to the ambiguous nature of the soma in many of the heterozygotes and to the relatively small number of offspring, it is useless to compare theoretical and observed distributions of plumage colors in the somas. Suffice it to say that white, buff, black, and Game-colored chicks all appeared in the F2 generation, as well as some with a mixture of colors, as called for by the hypothesis. White, due to the powerful graying factor, was the commonest color, buff and black were about equally common, and each about one-third as abundant as white, while Games, due to the hypostatic J factor, were about one-third as common as buff. All this, again, is explicable upon our hypothesis and upon none other so far proposed. In mating the F2 generation with each other or with the White Leghorn the result must vary with the gametic output of the hybrid, which is obviously very different in different cases. A hen, of a light buff color spangled with white