Effects of Temperature on Drosophila 305 

 150 (2110) 



A note on the effects of temperature on the mutant characters 

 "bent" in Drosophila virilis and Drosophila melanogaster. 



By C. W. METZ. 



[From the Carnegie Institution of Washington, Department of 

 Genetics, Cold Spring Harbor, N. Y.] 



The character "bent" in D. melanogaster is a member of the 

 "fourth linkage group" in that species. 1 The genes for this and 

 the other two characters now known in this linkage group have 

 been shown by Bridges 2 to be "carried" by the small, dot-like 

 "fourth chromosome." Bent is characterized mainly by two 

 variable modifications, one affecting the wings, the other the legs. 

 The wings vary from "normal" through a series of modified 

 shapes including spread wings, narrow wings, broad wings, 

 swollen wings and most frequently wings that are bent sharply 

 backward at a point near the base. The legs likewise vary from 

 a "normal" condition through a series of stages in which pro- 

 gressive degrees of shortening and twisting is exhibited, begin- 

 ning with the basal tarsal joint of the hind legs. The extent of 

 the modification seems to be influenced considerably by environ- 

 mental conditions. 



Some time ago I found in Drosophila virilis a mutant charac- 

 ter which bears considerable resemblance to this bent in D. mel- 

 anogaster both in appearance and behavior. It exhibits much the 

 same series of variable leg and wing modifications, except that 

 those of the wings are less extreme and less frequent — the sharp 

 bend being absent entirely. There are several lines of evidence 

 pointing toward the conclusion that these characters in the two 

 species are homologous, and that the gene for bent is in the small, 

 dot-like chromosome in virilis as it is in melanogaster. Most 

 of this evidence will be considered elsewhere, however. The 

 present paper deals primarily with the effects of temperature on 

 the two characters. 



Since the characters show indications of homology and are 



1 Muller, H. J., J. Exp. Zool., 1914, xvii, 325. 



2 Bridges, C. B., Proc. Nat. Ac. Sc., 1921, vii, 186. 



