134 c - L - TURNER. 



all brown-eyed progeny from brown-eyed by white-eyed crosses. 

 However, the expectation of 50 per cent, white-eyed and 50 per 

 cent, brown-eyed progeny was only approximately realized in the 

 preliminary experiments. 



B. EXPERIMENTS WITH PEDIGREED STOCK. 

 The strains used in these experiments were selected from 

 vigorous stock all the members of which had been recorded 

 through several generations. The white-eyed strain was one 

 which had been started soon after the discovery of the white-eyed 

 mutation and one which had been inbred from the start. The 

 brown-eyed stock w r as one which had produced only brown-eyed 

 individuals for eight generations. 



a. White-eyed by White-eyed Crosses. 



All progeny secured from white-eyed pedigreed stock was 

 white-eyed. About twenty-two thousand of these individuals 

 have been recorded. 



b. Brown-eyed by Brown-eyed Crosses. 



Pure brown-eyed by pure brown-eyed crosses have produced 

 only brown-eyed progeny. About sixteen thousand of such 

 individuals have been recorded. 



c. Brown-eyed by White-eyed Crosses. 

 Whenever pure brown -eyed were crossed with pure white-eyed 



individuals the resulting progeny were invariably brown-eyed. 

 About twelve thousand such progeny have been recorded. 



In the second filial generation of pure brown-eyed by pure 

 white-eyed crosses 15,086 individuals were obtained from 167 

 successful crosses. Of this total number 11,338 were brown-eyed 

 and 3,748 were white eyed. 



Back crossing the brown-eyed hybrid of the first filial generation 

 with the pure white-eyed parental stock was carried out suc- 

 cessfully thirty-seven times giving a total of 4,582 progeny of 

 which 2,304 were brown-eyed and 2,278 were white eyed. 



d. Discussion of Results of Experiments with Pedigreed Stock. 



The results obtained verify the supposition that the condition 

 represented by pigmenled compound eyes, Malpighian tubules 



