HEREDITY 



the F! generation, and (4) smooth and white, 

 a new variety (Fig. 25). It will be seen that 

 the pigmentation of the coat has no relation 

 to its smoothness. The dark animals are either 

 rough or smooth, and so are the white ones. 

 Pigmentation of the coat is evidently a unit- 

 character independent of hair-direction, and as 

 .new combinations of these two units the cross 

 has produced two new varieties, the rough 

 dark and the smooth white. 



Again, hair-length is a unit-character inde- 

 pendent of hair-color. For if a short-haired 

 dark animal (either self or spotted, Fig. 26) 

 be crossed with a long-haired albino (Fig. 27), 

 the Fj offspring are all short-haired and dark 

 (Fig. 28) ; but the F 2 offspring are of four 

 sorts, viz. (1) dark and short-haired, like one 

 grandparent, (2) white and long-haired, like 

 the other, (3) dark and long-haired, a new com- 

 bination (Fig. 29), and (4) white and short- 

 haired, a second new combination (compare 

 Fig. 25). 



Now the four sorts of individuals obtained 

 from such a cross as this will not be equally 

 numerous. As we noticed in connection with 



42 



