GENE AND CHROMOSOME MUTATIONS 235 



.!"' lighl-hiilicd agouH. — Allele of </. Like a' except that the back is 

 agouti instead of black. Morgan, 1915, Am. Nat. 49: 379 383. 



.P lethal yellow. — Allele of a. Mice heterozygous for A" have a bright 

 yellow coat and show a tendency to put on fat. Homozygous A^A^ mice 

 are non-viable, dying in the early stages of development. Little, 1919, 

 Am. Nat. 53: 185 187. Kirkham, 1919, J. Exp. Zool. 28: 125-135. 



ae absence of corpus callosum. — Brain lacks corpus callosum. Behavior 

 normal. Keeler, 1933, Proc. Nat. Acad. Sc. 19: 609-611. 



b brown. — Coat color cinnamon brown in combination with agouti, 

 chocolate in combination with non-agouti. Completely recessive except 

 in the genotypes sisi and pp in which it is partially dominant. Little, 1913, 

 Carnegie Instn. Wash. Pub. No. 179: 11-102. 



C color. — Chromosome i. Between sh-i (3.1% crossing-over) and p 

 (17.3% crossing-over). Griineberg, 1936, J. Genet. 2)2>'- 255-265. C is the 

 type allele of the albino series. 



c albinism. — No pigment in coat or eyes. Recessive to C except 

 that Ccpp mice are lighter than CCpp mice. Dunn, 1936, J. Genet. ^^ : 443- 



453- 



c* extreme dilution. — Allele of c. Coat quite light, eyes black, yellow 

 pigment suppressed. Recessive to C, partly dominant to c, c''^, and c'. 

 Detlefsen, 1921, Am. Nat. 55: 469. 



(■'''* chinchilla. — Allele of c. Coat lightened, but much less than by c^, 

 eyes black, yellow pigment suppressed, c"^^ has more effect on the coat of A 

 mice than of aa mice. Thus in aaB mice separation of c''V' from C is some- 

 times difficult, although with practice c'^V' may be distinguished by the 

 lesser saturation of black which tends to be dull and slate colored near the 

 base of the fur, and especially by the shade of the hairs lining the ears which 

 in C forms are yellowish, in c'^^c'''' creamy or nearly white. Again, in aabb 

 mice the genotypes C, c'^V' and c'^^c^ are indistinguishable, whereas if A is 

 present they can be separated. Recessive to C, partly dominant to c, c^ 

 and c'. Dunn, 1936, J. Genet. ^7^: 443-453- 



6"' intense chinchilla. — Allele of c. Similar to c'"'' but causes somewhat 

 less lightening of the coat. Feldman, 1935, J. Mammal. 16: 207-210. 



Ca caracul. — Chromosome 6. Linked with A (1.8% crossing-over). 

 Cooper, 1939, J. Hered. 30: 212. Vibrissae curled and coat wa\T. Recog- 

 nizable at one day after birth by slight curling of vibrissae. Less pronounced 

 in old mice than in mice with the first pelage but easily recognized by the 

 curled vibrissae and the waviness of the guard hairs. Very similar to Re. 

 Completely dominant to type. Carnochan, 1937, J. Hered. 28: ^2>2>~i6A- 



