26 



INHERITANCE IN GUINEA-PIGS. 



numbers were only 0.6 and 1.5 individuals respectively, so that their 

 absence was not surprising. 



By silver agouti F x females, c?517 had 9 young of 4 different color 

 varieties, the maximum number of classes expected being 6. 



By sepia F! females, cf517 had 35 young, distributed among 6 dif- 

 ferent color classes, as expected. Summarizing the results from all 

 three lands of matings, we find that the F 2 young of d"517 number 69, 

 distributed among 11 of the 12 expected classes of young, the missing 

 class being one in which the expectation is for 0.6 of an individual, 

 scarcely more than an even chance for the production of such an indi- 

 vidual in the number of young recorded. (See table 15.) 



TABLE 16. Young produced by red-eyed white parents mated inter se. 



A word as to the number of classes expected may not be out of place. 

 The dark-eyed classes expected are 6, identical with those expected 

 from the cross of race C animals with wild Cavia cutleri. (Compare 

 p. 16.) The number of classes expected among the red-eyed young is 

 1 less, namely 5, because red-eyed whites which have brown pigment 

 in the eye can not be distinguished (except by breeding-test or post 

 mortem) from those which have black pigment in the eye, the quantity 

 of pigment present being too small, and the coat in both cases white. 



On the whole the agreement between expected and observed in this 

 experiment is so good as to preclude the idea that any coupling or 

 association occurs among the 4 unit factors involved in the cross. 



This experiment produced 4 color varieties of guinea-pig previously 

 unknown to me, viz, the 4 red-eyed classes other than silver agoutis, 

 which had already been obtained from the uncrossed lea race. (See 

 plates 1, 2, and 5.) The eye has a similar appearance in all the red- 

 eyed classes, showing a deep-red glow by reflected light. The silver 

 agouti variety, as already explained, differs from golden agouti in the 

 ticking of the fur, which is white in silver agouti, instead of red or 

 yellow as in golden agouti. Sepia as compared with black has a more 

 faded appearance, approaching chocolate on the sides of ,the body and 

 belly, but always darker and unmistakably black above. Silver china- 



