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ROBERT L. KING. 



were also Dichsete indicating that D and Bl are probably in differ- 

 ent linkage groups (Table I.). 



F x Dichsete Bristle Lobe males were mated with wild type 

 females and F l Dichaete Bristle Lobe females were mated with 

 wild type males. The male black-crosses showed no recombina- 

 tion of Bl and L so that Bl is in the second linkage group. The 

 female back-crosses gave a cross-over value of 18.1 per cent, 

 between L and Bl (Table I.). 



TABLE I. 

 P l DICH^TE BRISTLE $ X LOBE <$. 



B. C, F 1 DicHvETE BRISTLE LOBE c? X WILD TYPE ?. 



B. C., F 1 DICH^ETE BRISTLE LOBE $ X WILD TYPE 



(DlCH^ETE NOT CLASSIFIED). 



In order to find the approximate location of Bl in the second 

 linkage group F t Bristle females from matings of Bristle X black 

 purple curved were back-crossed to black purple curved males. 

 The results (Table II.) show that Bl lies to the right of purple 

 and give the following cross-over values b-p 6.5 per cent; p-Bl 

 0.18 per cent.; Bl-c 14.6 per cent, and p-c 14.8 per cent. (The 

 standard values are b-p 6 per cent, and p-c 21 per cent. No ex- 

 planation was found for the discrepancy in the purple-curved 

 region.) As there were only three cross-overs between Bl and 

 p, one of which was also a cross-over between b and p (a rare 

 occurrence in 6.7 units) it seemed advisable to make further tests. 



