48 



THE INHERITANCE OF COLOR IN MICE. 



There should exist, according to the hypothesis advanced above, 81 types 

 of zygotes in the non-yellow self-colored races. A similar number of types of 

 albinos should also be formed. In the experiments here recorded no effort has 

 been made to obtain a large number of tj^pes of zygotes, yet 58 of the 81 pure 

 colored types have been met with. The occurrence of these 58 types is assured 

 by breeding tests, but it is almost certain that all 81 types have occurred many 

 times in the writer's experiments, since only a very small part of the animals 

 raised has been used for breeding. 



A table follows showing the numbers of possible zygotic types, and the 

 number of the observed types in the 16 self-pigmented non-j^ellow color varie- 

 ties which are homozygous in the color-producer (F). 



If yellow animals differ from the non-yellow by the presence of an epi- 

 static restriction factor, R, we should expect that the 81 zygotic types of non- 

 yellow mice would have their counterpart in the yellow series. Cuenot (1911) 

 recognizes this fact, but explains it in a slightly different way, which need not 

 be discussed here. 



Yellow animals corresponding with 14 of the 16 non-yellow color varieties 

 have been recognized in breeding tests. The yellows which arc potentially 

 dilute brown and those which are potentially pink-eyed dilute-brown agouti 

 are the only forms not as yet demonstrated by breeding tests. There is no 

 reason to suppose that these can not be produced, and it is almost certain that 

 they have occurred among my animals but have not happened to be chosen for 

 breeding. 



The gametic and zygotic formulae used in this part of the paper will be 

 identical with those employed in the first part. A set of abbreviations, given 

 on p. 50, will be used in tables. The results here tabulated follow the various 

 experiments through April 15, 1912. 



