ALLEN. — THE HEREDITY OF COAT COLOR IN MICE. 129 



5. 



bl.-ch + bl.-ch. = gametes of $ , 



\vh. (yell.-ch, latent) -f wh. (bl.-ch. latent) = gametes of 9> 



2 gr. + 2 bl. = Fi- 



In the one case (a), the gray character transmitted by the albino 

 is suflicient to produce only gray offspring. In the other case (6), 

 the gray character, latent in the albino, is supposed to undergo resolu- 

 tion so that gametes are formed one-half of which contain the yellow- 

 chocolate character and one-half the black-chocolate character. In the 

 two cases wherein the yellow character unites with the black of the black- 

 white parent, gray offspring result, since all three of the pigment elements 

 are thus brought together. In the other two cases, however, both unions 

 are of gametes having only the black-chocolate elements, and so only 

 black young result. If this hypothesis be correct, there should be on the 

 average 3 gray to 1 black young produced by the cross described. There 

 were actually obtained 43 young, so that the expected result is (32^ or) 

 32 gray to (10^ or) 11 black mice. The observed result was 28 gray to 

 15 black, a fairly close approximation. 



In a second case a black-white male having albinism recessive was bred 

 to these same albino females. Assuming, as before, that in one-half the 

 cases the gametes of the albinos contained the gray character, and that in 

 the remaining cases the gray had been resolved, the combinations of 

 gametes to be expected are : 



a. 

 bl.-ch -f- bl.-ch. = gametes of ^ , 



wh. (gr. latent) -f- wh. (gr. latent) == gametes of 9 , 



2 gr. -f- 2 wh. (gr. latent) = Fj. 



h. 



bl.-ch. + bl.-ch. = gametes of ^ , 



wh. (yell.-ch. latent) + wh. (bl.-ch. latent) — gametes of 9, 



1 gr. + 1 wh. (gr.) + 1 bl. -h 1 wh. (bl.) = Fi. 



The expected result is therefore : | \ ^];![^ [gl-ay^lten"? + ^ S''^^ + 

 1 black. The actual result was 21 albinos 4- 10 gray -f 2 black. The 

 albinos are here in considerable excess, but if the 12 pigmented individ- 

 uals are alone considered the expected result would be 9 gray to 3 black 



VOL. XL. — 9 



