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Show 74 MR. W. BATESON ON COLOUR-HEREDITY [May 26, 8. Cream. Diluted yellow. 9. Black. Both black and brown present, without yellow. The bases of the hairs are the darkest, and the black does not extend to the tips of the large contour hairs, which are brown. Hairs behind the ears or on belly are a still lighter brown. Complication arises from the fact that at least two kinds of black exist, known as " black " and " sable-bred black," viz. thrown by sables. These two kinds probably differ in their heredity-properties. Pied forms common. 10. Blue. Diluted form of (9); both black and brown pigments coexisting. Blues may be thrown by the " blacks" (not sable-bred) and then breed true. Pied forms exist. 11. Albino. No pigment in any part. As albinos, however produced, breed true to the albino character generally, if not universally, individuals of dissimilar origins are often mixed together. One strain at least, that of Mr. Atlee, is recognised in the fancy as having special features of size and shape, and has been kept distinct for many generations. 12. Black-eyeol white. Strains of this type have been independently produced twice, perhaps oftener. The degree of pigmentation in the eye varies in at least one strain, some eyes being full black, others looking blackish red. Whether the type ever breeds quite true we cannot say. In our experience offspring with small black marks occur (compare phenomenon seen in albino Guinea-pig, p. 76). 13. Variegated. In these, irregular small spots of black or chocolate occur on a white ground. Such forms are quite distinct from the ordinary piebald and Dutch-marked (viz. like the Dutch rabbit) combinations of colour with white. In comparing colours care must be taken that specimens are of similar age and in similar moult-stages. Differences of intensity of colour are of course characteristic of different strains, and probably intermediates can be found ; but there is no doubt of the practical distinctness of each of the forms enumerated. " Brindling," viz. lighter or even white hairs distributed as ticking, occurs in some of the coloured varieties, as in rabbits, but we have not been able to examine specimens, As to the age and mode of origin of the several forms little is known certainly. Several conditions are plainly clue to resolution of compound characters, such as often follows crossing in animals and plants. The blue, the black-eyed white, and the variegated are certainly productions of the last few years ; the rest (? sable) have existed for a long time. The question how far M. sylvaticus has been used in the production of the varieties is a very important one. The experiment was suggested many years ago in ' Fancy Mice' and has probably been often tried. Mr. Atlee has given m e a most circumstantial account of a cross with this species made by him nine years ago on black-and-white does, and I feel no reasonable doubt that it |
