COLOR 



57 



is represented in rabbits 3 1160 and 9 1171, bora in the same litter with 9 1161 

 and $ 1172 of variety 4 (p. 55). When mated with each other they produced 7 

 gray, i black, 2 yellow, i sooty, and 5 white young. Other rabbits of this variety 

 were produced by the Belgian hare (9431) in a mating with an albino rabbit 

 (c? 56). These gray rabbits (2 males and 3 females, 232 to 236), when mated 

 inter se produced 17 gray, 5 black, 6 yellow, 2 sooty yellow and 6 white young, 

 the expected Mendelian proportions being 27 : 9 : 9 : 3 : 16. When mated with 

 albinos these same gray rabbits produced 9 gray, 6 black, 2 yellow, and 16 

 white young. The zygotic composition of the albino mates in this case is not 

 fully known, so that the theoretical proportions of the pigmented young can 

 not be stated. The albinos are as expected approximately half the total young, 

 and all expected color varieties are represented except sooty yellow. 



TABLE 36. Matings and young of 9 178, gray. 



1 Plus 3 yellow or sooty, died young. 



For simplicity the young of all 5 gray rabbits are grouped together in the 

 foregoing account. In reality, however, one of the males was heterozygous in 

 factor U, and at least i male and i female were heterozygous in factor I, as is 

 shown by the facts (i) that several of the young produced in matings with white 

 individuals bore spots of white, the whitest of all being belted with white ("Dutch 

 marked"); and (2) that one of the gray offspring of the gray parents was of a 

 pale blue-gray color. 



(9) The gray rabbits just described, which produced a blue-gray young one, 

 in reality belong to a ninth variety of gray rabbit, indistinguishable in appear- 

 ance from the other eight, but producing a different assemblage of young, viz, 

 dilute-colored as well as intensely colored young in each of the pigmented vari- 

 eties, and also albinos. The whole assemblage of visibly different varieties is 

 gray, black, yellow, sooty yellow, blue-gray, blue, pale yellow, pale sooty yellow, 

 and white. Not all of these varieties were obtained directly from the pair 

 of rabbits in question, doubtless because too small a number of young was 

 produced, but in later generations all were obtained. Thus from the single 

 blue-gray individual, when mated within the same family, were obtained blues, 

 pale sooties, and pale yellows, as well as individuals of normal intensity. The 

 zygotic formula of this ninth variety of gray rabbit is B 2 Br 2 E(R)ACI(D)Y 2 U 2 . 

 Since it indicates a heterozygous condition in 4 character-units, we should 

 expect a pair of individuals of this formula to produce 16 different gametic 

 combinations. Eight of these are represented in the enumerated 8 classes of 

 pigmented young, 8 others would occur among the albinos which would differ 

 from the pigmented classes in the absence of C, but all of which would look 

 alike, though breeding differently in crosses with pigmented animals. 



