On the varying dominance of certain wliite breeds of the silk-worm, etc. 28 1 



F3 of the latter 3 w : i Y brood. 



The zygotic constitutions of this brood are the same as F3 of 

 monohybrid and its posterity will be normal F4 and so on. 



c) The third Fi whites whose zygotic composition is WW, Ww and 

 WY will produce six kinds of F2 broods as just described above. 



In F3, all the offspring derived from all white Fg broods will 

 remain true to parents except combination "d" which composition is 

 the same as the dominant form of F2 of monohybrid. To the offspring 

 of two sorts of 3 w : r Y broods reference has been already made in 

 the former pages. 



Thus the order of inheritance displayed by the series of double 

 matings above referred to will graphically be represented as below: 



Dominant white female mating. 

 A whites. 



F, all \V. {WW + WY) 



all W. (? W : I V) 



all W. (3 W : I Y) all W. (3 W ; i Y) all Y. 

 B whites. 



all W. (Ww + WY) 



Ö~W '. ~ ~ 



F3 all W. all W. (3 W : i V) (3 W : 1 Y) (i W : 3 Y) all W. (3 \V : i Y) all Y. 



C whites. 



Fl all W, (WW, Ww. WY), 



Po all W. (~~\V ': ~) (3 W : I Y) 



F3 allW. (3W:iY) all W. (3 W: I Y) (3 \V; i Y) (iW:3Y) ^|'_ (3W:iY) ''!;l[ 



For the sake of comparison we quote here Kellogg's results. Of his 

 seven double matings only two gave all white F^ which paired h/fer 

 se produced the following offspring. 



I. Bagdad white females doubly mated with its own white and 

 Istrian yellow males. 



