UNIT-CHARACTERS (GENE MUTATIONS) 23 



The chinchilla mouse with black agouti coat may be 

 described (157) as a bluish gray containing no yellow, its 

 pelage resembling closely that of the gray squirrel. Brown 

 agouti animals containing the chinchilla factor (see Fig. 14) 

 are easily distinguished by their brownish coat, with white 

 rather than yellow bands of the agouti distribution pattern. 



Chinchilla has a tendency to remove yellow from the coat, 

 although it also dilutes black and brown pigments, changing 

 non-agouti black to sepia. This leaves parts of agouti hairs 

 almost white and the bellies of agouti chinchilla animals are 

 usually quite colorless. 



The yellow-reducing tendency is easily demonstrated by 

 the fact that when lethal-yellow mice are crossed with 

 chinchillas and yellow animals are produced carrying two 

 doses of chinchilla, these animals have a cream coat and 

 black eyes. 



Chinchilla (157, 57) of the mouse corresponds to chin- 

 chilla of the rabbit both in appearance and genetic behavior, 

 being in both cases produced by a form of the albino gene 

 recessive to normal pigmentation and dominant to both 

 extreme dilution (Himalayan) and true albinism. 1 



Pink-eyed dilution (p) 



Scaliger saw another (mouse) very bright, with flaming eyes. — John- 

 son, 1640. 



This mutation (see Fig. 27) reduces greatly the black or 

 brown pigment, giving the eye a beautiful pink tint, from the 

 color of the blood in the eyeball. The coat of the agouti 

 black is changed to a fawn. The coat of the agouti brown 

 (cinnamon) becomes also a fawn but more brilliant than the 

 pink-eyed black agouti, because brown pigment replaces 



1 Dr. C. Carter Blake (Fancy Mice, fourth edition) in a letter written about 

 1890 describes two crosses in which albinos mated with albinos produced colored 

 young. His results may be explained if it be assumed that the male used was really 

 a synthetic albino homozygous for pink-eye, heterozygous for non-agouti, brown, 

 and spotting, and bearing one dose each of chinchilla and albinism. If this be the 

 true explanation of these crosses, then human experience with chinchilla antedates 

 Schuster's crosses in which chinchilla came in heterozygously from a gray mouse 

 caught in the wild. 



