ALLEN. — THE HEREDITY OF COAT COLOR IN MICE. 143 



The albino male, 254, gave gray animals on being bred to the choc- 

 olate female, 2G4. Those gray oil'spring, bred inter se, produced in 

 three litters, 1 chocolate, 2 goldeu-agouti, 2 black, 12 gray, and 5 albino 

 young. 



It is difficult, iu view of the small number of young obtained, to formu- 

 late a wholly satisfactory hypothesis to account for the combinations of 

 color characters which here took place. The chocolate offspring are to 

 the other pigmented young as 1 : 1 6 instead of being as 1 : 3, the expected 

 ratio. Apparently, a certain number of gametes bearing the black 

 character were produced by the gray heterozygotes, and some of these 

 gametes may have united with those bearing the chocolate character, 

 thus producing black offspring, wliile at the same time reducing the 

 number of pure chocolate individuals. The large proportion of gray 

 young may indicate either the presence of unresolved gray in some of 

 the gametes, or the recombination of the three elements of a gray which 

 underwent resolution at gamete formation. The white male, 2.54, must 

 have contributed the characters other than chocolate which appear in 

 his grandchildren. 



The occurrence of a few black mice in crosses between chocolates and 

 certain albinos has been mentioned. The ancestry of two of these black 

 individuals, which were saved for further testing, is as follows : 



$ wh. 9 house mouse 



$ gr. 51 9 wh, $ bl.-wh. 1 • 2 b. 9 wh. 



$ wh. 145 9 wh. 141 $ gr. 82 9 gr, 81 



S wh. 285 9 ch. 284 



(? bl. 326 9 bl. 357 



If the chocolate parent produced only gametes having the chocolate 

 pigment character, these black individuals must have resulted from the 

 union of such a chocolate gamete with one from the albino containing 

 the black character, and hence must be heterozygous with respect to the 

 two characters. The albino was descended from a stock of albinos 



