On the varying dominance of certain white bneds of the silk-worm. etc. 2SQ 



Table IV. 

 Crosses between Japanese yellow females and European wliite males. 



That is to say, 3 matings yielded all white Fj broods, and there- 

 fore the white is dominant towards the yellow in these matings, 

 while the rest gave mixed F^, the proportion of white and yellow 

 being i: i. 



As the Japanese yellow is homozj'gous and the European white 

 a mixture of homozygous and heterozygous, we may represent the 

 former by "YY" and the latter "ww" or WY. If a mating takes 

 place between homozygous dominant white (WW) and yellow (YY) the 

 result would be "wY" or all white F^ offspring while heterozygous 

 white (\W) mated with yellow (YY) would produce 



WY X YY = WY + YY = I white : i yellow, 



that is to say, a mixture of one white and one yellow. 



Tliis may serve to explain the results above mentioned. 



in. Japanese white x European white. 



Lastly we shall see the result of crossing between. Japanese and 

 European whites. The formers are divo'.tine (Shinkawac/ii, Aojiku 



