THE AMEBIC AN NATURALIST [Vol. XL V 



TABLE I 



White [heterozygous, w(y)] x Yellow <? [homozygous, yy] 

















Wild, yellow 





3 



2 



5 



3 

 10 



Total in 1908 and 1909 





17 § § 



369 9 









22 

 15 



9 



8 

 13 



Wild, white A 

 u D 



Wild, yellow 



1910 a 



d 



79 

 30 



Total in 1 ill \b\ $ g 



615 5 



589 9 



3. If a heterozygous white female is crossed with cer- 

 tain other yellow males, her brothers and the sons of the 

 same white female, that are heterozygous for color (as 

 indicated by the fact that when mated with homozygous 

 yellow females both white and yellow offspring result), 

 a larger number of white females than of yellow are 

 produced, though not three white to one yellow according 

 to Mendelian expectation. The proportion observed is 

 approximately two to one (viz., 38 :22, 13 :8, g and h, 1910, 

 and probably the 8:4 of family 2w, 1909). This propor- 

 tion may be explained, as Dr. Castle first suggested to 

 me, by assuming that in these families no homozygous 

 whites occur, through infertility or abortion of the 

 " white" germ cells that would naturally combine with 

 white, so that the offspring consist of : 



