ALLEN. — TIIK HERKDITY OF CO^VT COLOR IN MICE. 155 



D'R, DRK, iuul R. Most of these classes have been demonstrated to 

 be actually present. 



// If the hypothesis advocated by Cuenot be correct, that pigment is pro- 

 fluced by the action of specific ferments on a chromogenic substance, and 

 that albinos carry tlie former but not tlie latter, then it must be assumed 

 that the two characters opposed in a cross of a i)igmented with an albino 

 form .arc: (1) presence of chromogenic substance, and (2) absence of 

 chroraogenic substance. At all events albinos may transmit pigment- 

 characters, even though they themselves show no trace of pigment. 



All albino that transmits the character })artial pigmentation may be 

 looked upon as potentially a spotted mouse in whose soma the pigmented 

 areas do not show, [lerhaps because the necessary chromogenic substance 

 is lacking. The spotted condition may be due to a decrease in the 

 amount of both the chroraogenic substance ami the specific ferments as 

 compared with the amounts of these substances in a totally pigmented 

 y animal . 



2. Pigments. (1) The gray coat of the house mouse contains the ] 

 three pigments, black, chocolate, and yellow, as has been stated by • 

 Bateson (: 03''), and this combination as found in the wild animal is 

 strongly dominant over any of the colors shown by fancy varieties (with 

 the possible exception of yellow, which the writer lias as yet had no 

 opportunity to test). Therefore when wild gray animals are bred to 

 varieties of other colors, gray offspring result. 



By interbreeding gray heterozygotes, themselves from a cross between 

 gray house mice and albinos, a few black offspring were obtained, 

 indicating that a resolution of the gray color may have taken place in a 

 few cases. No further resolution of the gray from house mouse crosses 

 was ol)tained. 



In the case of gray heterozygotes resulting from a cross of fancy 

 black-white with albino mice, resolution took place to the extent of pro- 

 ducing the golden-agouti and the chocolate, as well as the black type. 



(2) Animals of the black type breed true to that color. This state- 

 ment holds good even if one or both of the parents contain albinism 

 recessive. For in this case the gametes having the albino character 

 carry also the specific "ferment" or whatever it may be, that stands 

 for black. • 



It follows that an albino, both of whose parents are black, transmits 

 the black character. Such an albino, bred to black animals, is found to 

 give young having the black-chocolate pigment-characters only. 



Black mice bred to albinos of gray or of mixed ancestry produce 



