The conclusion that right and left conditions are not simple, alternative qualities accords with the results obtained by others. Thus Larrabee (1906) finds that the dimorphism of the optic chiasma of fishes (in some cases the right optic nerve being dorsal and in others the left) is not at all inherited, but in each generation the result is strictly due to chance. This is, perhaps, the same as my conclusion that the hereditary factors are complex. Lutz (1908) finds that in the mode of clasping the hands interdigitally the right thumb is uppermost in 73 per cent of the offspring when both parents clasp with right thumb uppermost, but in only 42 per cent of the offspring when both parents clasp with left thumb uppermost. The mode of clasping is inherited, but not in simple Mendelian fashion. CHAPTER X. PLUMAGE COLOR. A. THE GAMETIC COMPOSITION OF THE VARIOUS RACES. Plumage color, like hair color, varies greatly among domesticated animals. This diversity is, no doubt, in part due to the striking nature of color variations, but chiefly to the fact that the requisite variations are afforded in abundance. The principal color varieties, in poultry as in other domesticated animals, are melanism, xanthism, and albinism. In addition, poultry show the dominant white, or "gray" white, first recognized in poultry by Bateson and Saunders (1902), which is also found in many mammals, as, for instance, in goats, sheep, and cattle. Besides these uniform colors, we find numerous special feather-patterns, such as lacing (or edging of the feather), barring, penciling, and spangling. Also, there are special patterns in the plumage as a whole, such as wing-bar, hackle, saddle, breast, and top of head (crest). Now, all of these color characters are inherited each in its own definite fashion. In studying the color varieties of poultry we must first of all, as in flower color (Correns, 1902), mice (Cuénot, 1903), guinea-pigs and rabbits (Castle), various plants and animals (Bateson and his pupils), recognize the existence of certain "factors." In poultry the factors that I have determined are as follows: _C_, the color factor, absence of which results in albinism. _J_, the Jungle-fowl pattern and coloration. _N_ (nigrum), the supermelanic factor. _X_, the superxanthic or "buff" factor. _W_, the graying (white) factor. We have now to consider how these factors are combined in birds of the different races. 1. WHITE. _Albinos._--These seem to be of two different origins:[9] White Cochins and white Silkies. The white Silkies that I have studied have the gametic formula _cJnwx_; _i. e._, they have the Jungle-fowl marking, but lack the "color enzyme," supermelanic coat, the graying factor, and the xanthic factor.