468 



ROBERT L. KING. 



cross-overs and show that homozygous Bristle is not viable. This 

 is further shown by the inbreeding of F x Bristle males and females 

 from a cross of Bristle purple (from Table II.) with wild type. 

 No purple offspring appear because purple is so closely linked to 

 Bristle. Bristle does not represent a deficiency toward the purple 

 region at least. A balanced lethal stock with Bristle and Lobe 

 linked, balanced against Curly has been made up and should prove 

 of some value in quickly locating genes in the second linkage group. 



TABLE IV. 

 BRISTLE ? X BRISTLE <$ (FROM TABLE I.). 



Bl. 

 416. 



Wild Type. 



.213 



P 1 , BLA<?K BRISTLE CURVED <$ X WILD TYPE ?. 

 F x Bristle <$ and $ inbred. 



P 1 BRISTLE PURPLE $ X WILD TYPE 

 F 1 Bristle J and ? inbred. 



Bl. 



74- 



Wild Type. 

 ....56 



SUMMARY. 



1. A new bristle form in Drosophila melanogaster has been 

 found and named Bristle, Bl. 



2. The mutant gene is a dominant, lethal when homozygous. 



3. The locus of Bl lies 0.18 per cent, to the right of purple at 

 approximately 54.8 in the second linkage group. 



4. A stock of Bristle Lobe balanced against Curly has been 

 made up and is available for use. 



BIBLIOGRAPHY. 



Bridges, C. B., and Morgan, T. H. 



The second chromosome group of mutant characters. Publication 278, 



Carnegie Institute of Washington, p. 123. 

 Plough, Harold H. 

 '17 The Effect of Temperature on Crossingover in Drosophila. Journal 



of Experimental Zoology, 24: 143. 



