A NEW SEX-LINKED CHARACTER IN DROSOPHILA. 223 



TABLE III. 



Gametes of Fi barred 9 , A br'X Br'. 

 Gametes of Pi barred d" , X Br'- 



Females. Males. 



A Br' fA br' {X br' fA Br' 



A Br' \X Br' 



Barred $. Normal cf- Barred 



281 159 



In the experiments recorded in Tables II. and III. it was 

 noticed that the barring was of two kinds: (i) A very narrow 

 bar (Figs. I and 2) which appeared in all barred males, and in 

 about one half of the double class of barred females, and (2) 



W Br' 



X 



w br' 



V_ Br' 



X 

 v br' 



W V Br 



X X 



br' 



DIAGRAM i. (a) Showing loci of white (w) and barred (br') in sex chromo- 

 somes of heterozygous female, with the loci of their normal allelomorphs. Crossing 

 over is indicated by the X between the lines, (b) Ditto for vermilion and barred. 

 (c) Ditto for white, vermilion, and barred. 



a bar not so narrow which was present in the rest of the females. 

 The loss in the latter case was mainly on the anterior edge and 

 was especially noticeable as a single notch, or two notches, 

 giving the eye a decided heart shape (Figs. 5 and 6). Here also 

 the ommatidia are disturbed from their regular geometrical 

 arrangement, and converge in rows to the notch. The difference 

 in the narrow and broad bars is due to a difference in zygotic 

 composition for, as will be described later, breeding tests have 

 shown that invariably the broader types are heterozygous in 

 barring (Br' br'}. When the narrow bar females were bred to 



