^36 



THE AMERICAN MUSEUM JOURNAL 



If three pairs of characters are concerned 

 there will be, typically, eight classes of 

 offspring, in the F2 generation. This is 

 seen in the third exhibit (page 237) illus- 

 trating inheritance of color and pattern 



in rats where, again, only samples of the 

 various classes are shown. Frequently, 

 as in the case of the rats, the breeder is 

 able, by crossing known varieties, to get 

 new or hitherto unknown ^•arieties in Fo; 



From exhibit in the American 

 Museum of Natural History 



DUPLEX INHERITANCE IN RATS 

 The iwo i.airs of .haracters Ji.-rf involved arc black versus yellow, and self-colored versus hooded, black and 

 self-olored bein^ don.inani , respeclivcly, lo yellow and hoo.led. The first-generation offspring are all gray hybrids, 

 ea<:l. with four different kin.ls of germ cells, which produce in the following generation four k.n.ls of individuals, 

 as in the case of the poinice flies. (Jne only of each kind is shown 



