278 



Multiple Alleles 



ferent alleles in them. In the first series there were 36 different 

 alleles; in the second series, 39 were different. 



Chinchilla, Himalayan, and Albino 

 Mammals 



Another example of a similar series 

 of multiple alleles in related species is 

 the albino series in several animals. 

 In each species, full color, C, is domi- 

 nant to complete absence of pigment, 

 c. This latter condition, known as 

 albinism, results in white animals with 

 pink eyes. Albinism in many other 

 animals and in human beings is the 

 result of a completely recessive gene. 

 In rabbits, mice, and guinea pigs, there 

 are two conditions intermediate be- 

 tween the full color and albino ex- 

 tremes. The full color, "gray," or 

 wild type is a blend of yellow and 

 black pigment. The intermediate 

 type, known as chinchilla, is less in- 

 tensely colored, having somewhat less 

 of the black pigment and almost none 

 of the yellow. The Himalayan type 

 has a white body and pink eyes like 

 the albino, but has black ears, feet, 

 tail, and nose. These types result in 

 each of these animals from a series of 

 four alleles, C (self-color), c^'' (chin- 

 chilla), c^ (Himalayan), and c (al- 

 bino). Each member of the series is 

 dominant over the others in that order. 



Fig. 82. Multiple alleles for coat color in cats. The normal type (with 

 the tabby gene) is at a; silver, corresponding to chinchilla in the rabbit is 

 at 6; at c is the Burmese type resulting from an allele not found as j^et 

 in the rabbit ; the Siamese cat, d, results from an allele apparently identical 

 with the one that produces the Himalayan rabbit. The albino has not yet 

 been found in cats. (Compare with Fig. 12. From Keeler in the Journal 

 of Heredity.) 



