COLOR 67 



resented in our c?45 (plate i, fig. 3), which when mated with the sooty 

 lop (plate i, fig. 2) produced 8 young, all black. One of these is shown 

 in plate i, fig. i. When mated with black 9 105, he produced 8 black pig- 

 mented and 3 Himalayan albino young, but several of the pigmented 

 young were spotted with white, this character being recessive in 9 105, 

 which had a Dutch-marked father. 



Variety 5 is represented in 9 269, which when mated with sooty <? 402 

 produced i gray and 3 black young (expected i: i). When mated with 

 yellow <? 179 (variety 3) she produced in one litter 3 black young, and in 

 a second litter, 3 gray and i black. This second litter, in which the 

 expected proportions of gray and of black young are exactly realized, is 

 shown in plate 2, fig. 6, the parents being shown in figs. 5 and 8 of the same 

 plate. 



Variety 8 is probably represented in $ 268 which when mated with yellow 

 <?3iQ (variety 3) produced 2 gray, i yellow, 2 black, and 2 sooty young 

 (expected i: i: i: i). The only other possibility is that this female was 

 of variety 7, which should in this mating produce the same varieties of 

 young, but in the proportions, 9:3:3:1. 



Variety 8 (but heterozygous in C', the Himalayan factor) is represented 

 in 9 108, which when mated with black c? 104 (variety 4) produced 3 

 black, 3 sooty, and 6 Himalayan albino young, exactly the expected pro- 

 portions. By yellow <? 179 (variety 3) she produced i gray, i yellow, 

 and i sooty young (expected i : i : i : i black). 



The foregoing cases would afford confirmation (if confirmation were 

 necessary) of the discovery by Cuenot (: 03) and by Hurst (: 05) that albino 

 mammals transmit color factors, and that they vary in zygotic composi- 

 tion as regards color factors. That albinos transmit the factor A is shown 

 by the observation that some of them (which bear A) produce gray off- 

 spring in crosses with black pigmented animals, while others (lacking A) 

 never produce gray offspring, though mated to the same black animals. 



That albinos transmit the factor E is shown clearly by extensive experi- 

 ments with guinea-pigs carried out by one of us. One family of albino 

 guinea-pigs has been found invariably to produce black offspring in mat- 

 ings with any pigmented variety devoid of factor A, whether that variety 

 has the extended or the restricted distribution of black or brown pigment; 

 a second family of guinea-pigs, with equal uniformity, produces colored 

 offspring having a restricted distribution of black pigment, if crossed with 

 colored individuals having the restricted distribution. This second vari- 

 ety produces black-eyed yellows, if crossed either with black-eyed yellow 

 or with brown-eyed yellow individuals. Of the 2 albino varieties men- 

 tioned, the first evidently carries B with E, the second B with R. 



These same two families of albino guinea-pigs likewise differ in factor 

 I, which is present in the first family, but replaced by D in the second. 

 If each is crossed with pale yellow (cream) individuals, the former produces 





