A MUTATION IN THE MOTH-LIKE FLY. 



and ocelli is dominant and the condition representing a lack of 

 pigment is recessive. Since the results Avere uniformly inde- 

 pendent of sex it follows that there is no sex linkage. The ratio 

 expected in the second filial generation of a pure brown-eyed by 

 pure white-eyed cross would be three brown-eyed to one white- 



1 individual. The ratio realized (3.032 to i) is near enough 



Hie tl . al ratio to demonstrate that Mendels La\\ is 



This is still further supported by the results from 



k crossing heterozygous brown-eyed stock with homozygous 

 white-eyed stock. In terms of Mendel's Law it \\ul<l K 



ected that one half of the progeny would be white-eyed and 

 one half brown-eyed. A close approximation to tin.- ratio \\ s 

 n-ili/ed \\heii out of a total of 4,582 individual- 2.304 \\ 

 br<i\vn-e\ed an< 3 2,278 were white-eyed. 



I Allowing is a diagram illustrating the correlation of experi- 

 mental results with expectations according to Mendel'- l.a\v for 

 d by white-eyed crosses. The number of individuals 

 obtained in the experiments are shown in parenthe 



BB- 



>bb 





brown-eyed 

 (12,000) 



Bb- 



73 ', 1 a own-eyed 



M.;;- 



2 5 c c white- eyed 

 (3,748) ' 



bb 



Bb 



50% 

 brown- 

 eyed 



(2,304) 



bb 



5"' 

 \vhite- 



eyed 



