204 



CHARLES ZELENY 



2. The components of the bar series 



The relative sizes and facet numbers of the different eyes are 

 shown in figure 1. Full eye (F), bar (B), and ultra-bar (U) are 

 sufficiently distinct for purposes of indentification, and the same 

 may be said of the heterozygotes. Hi is the heterozygote con- 

 taining one bar and one full factor, while H2 has one ultra-bar 



F 



B 



U 



H, 



Fig. 1 Eyes of females of Drosophila melanogaster Meig. F, full eye as 

 found in wild flies; B, bar eye in unselected stock; U, ultra-bar eye with typical 

 separation into two parts; E, emarginate eye, produced by the bar factor plus 

 accessory factors; Hi, heterozygote of full x bar; 112, heterozygote of full x 

 ultra-bar. 



and one full factor. £", emarginate eye is not a member of this 

 allelomorphic series, but is due to an accessory factor added to 

 bar. Full-eye females at 27°C. have a mean facet number of 

 810.6, and at the same temperature unselected bar ha,s 58.8 and 

 ultra-bar 22 facets. The dominance likewise shows an inten- 

 sification. Bar in crosses with full has a dominance coefficient 

 of 0.23 and ultra-bar one of 0.85 when complete dominance is rep- 

 resented as 1.00 and complete recessiveness as 0.00 (Zeleny, '20). 



