40 COAT CHARACTERS IN GUINEA-PIGS AND RABBITS. 



Although the discovery of the differences among albinos, as regards 

 matings with red animals, was made by mere accident while comparing 

 the matings of cT 635 with those of other albino males, I have since 

 found it possible to produce at will albinos free from latent black (like 

 cf 1999) by beginning with matings between ordinary albinos (all of 

 whose gametes transmit latent black) and red or yellow animals. The 

 following case illustrates the method used : Albino c? 2002 is shown by 

 matings recorded in Table D to form only gametes transmitting latent 

 black. For by red or yellow females he has produced 10 pigmented 

 young, all with more or less black in their coats. From the mating 

 with yellow ? 2001 there resulted 3 black-yellow young, 9 ? 2033- 

 2035. Each of these, according to the hypothesis offered, received 

 from one parent albinism with latent black, and from the other yellow 

 free from black. In forming gametes the yellow-black hybrids should 

 produce gametes of four different kinds, all equally numerous (on the 

 hypothesis that albinism is inherited independently of specific pigments, 



alb. & 2002 x yel. ? 2001 



bl.-yel 99 2033-2035 yel. 2061 

 I I 



III I I II 



yel.^1346 yel. & 1347 yel-9l348 yel. <j>1349 yel.? 1350 ye!.-wh.$ 1351 3 bl.-yel. young 



(alb. recessive) (pure) (alb. recessive) (pure) (pure) (alb. recessive) 



FIG. 10. A genealogical table ; for description, see text. 



as previously explained, viz, (i) yellow, (2) black, (3) albinism [yellow 

 latent], (4) albinism [black latent]. Accordingly, when a mating 

 of such a hybrid is made with a pure yellow animal, such as cJ 1 2061 

 (see fig. 10), gametic unions of four different sorts should occur with 

 equal frequency, viz, (i) yellow + yellow, producing pure yellow 

 young; (2) black -(- yellow, producing black-yellow young free from 

 recessive albinism ; (3) albinism [yellow latent] + yellow, producing 

 yellow young (with albinism recessive) ; (4) albinism [black latent] + 

 yellow, producing black-yellow young (with albinism recessive). That 

 is, half the young should be yellow, half should be black-yellow ; and 

 of each sort half again should contain recessive albinism, half should be 

 free from it. In the case under discussion (see diagram, fig. 10) there 

 were produced 6 yellow and 3 black-yellow young, but in a series of 

 matings equality of the two classes would undoubtedly have been more 

 closely approximated, as Table E indicates. The yellow young alone 

 were tested for the presence of recessive albinism, and it was found in 

 exactly half of them, viz, ? ? 1346, 1348, and 1351, the test indicating 

 that the other three yellow young are pure. The method by which 



