24 LABORATORY MOUSE 



black. Pink-eyed dilution (32, 23, 19, 5Ji) changes non- 

 agouti black to "lilac" and transforms chocolate to "cafe au 

 lait." 



That pink-eyed dilution works only upon black and brown 

 pigment is demonstrated by the fact that the coat color of 

 lethal yellow is almost unchanged by the addition of pink- 

 eyed dilution although the black eye of the lethal yellow is 

 changed to pink. 



Non-agouti (a) 



As to color, many are like the ass; however some are einerous, others 

 even black, others from brown to red. — Johnson, ] 640. 



Non-agouti (see Fig. 17) is due to a mutation resulting in 

 loss from the individual hairs of the normal banded distribu- 

 tion pattern determined by the gene A. No yellow apical 

 band is formed in the non-agouti animal, but the black or 

 brown pigment extends the full length of the hair. Absence 

 or inactivation of the agouti gene (A) in the mutant type 

 non-agouti (53, 54) (aa), changes a gray mouse to black and 

 a cinnamon to rich chocolate. 



Lethal yellow (A y ) 



In my cultures I found in addition yellow mice. ... — Cuenot, 1902. 



Presence of the yellow mutation (see Fig. 16) in a mouse 

 is easily recognized by its brilliant yellow coat and jet-black 

 (or brown) eye. These effects are due to the complete or 

 nearly complete suppression of black pigment, save in the 

 eye. In the eye of a yellow mouse black pigment is even 

 more abundant than in that of a black mouse, as proven by 

 clearing specimens of both types in xylol. 



Yellow is a dominant character, i.e. it requires but one 

 dose of the gene to cause the animal to exhibit the character. 

 Animals containing two doses of the yellow gene (homozy- 

 gotes) are inviable (15, 24, 10^, 20, 79). Thus, as the yellow 

 gene is an allelomorph to the agouti (166) (A) and non- 

 agouti (a) genes, a yellow mouse will contain one dose of 

 yellow and one of either agouti or non-agouti (A 1 A or A* a). 



