NEW DATA. 



DEPRESSED. 



67 



Several mutations have appeared in which the winj!,s are not flat. 

 Of these the first that appeared was curved (second chromosome), 

 in which the wings are curved downward throughout their length, but 

 are elevated and held out sidewise from the body; the texture is thinner 

 than normal. The second of these wing mutants to appear was jaunty 

 (second chromosome), in which the wings turn up sharply at the tip; 

 they lie in the normal position. The third mutant, arc (second chro- 

 mosome), has, as its name implies, its wings curved like the arc of a 

 circle. The fourth mutant, bow (first chromosome, fig. c), is like 

 arc, but the amount of curvature is slightly less. The fifth mutant, 

 depressed (first chromosome, fig. g), has the tip of its wings turned 

 down instead of up, as in jaunty, but, as in jaunty, the wing is straight, 

 except near the tip, where it bends suddenly. Ihese stocks have been 

 kept separate since their origin, and flies from them have seldom been 

 crossed to each other, because in the succeeding generations it would 

 be almost impossible to make a satisfactory classification of the various 

 types. But that they are genetically difi^erent mutations is at once 

 shown on crossing any two, when wild-type oftsprmg are produced. 

 For instance, bow and arc are the two most nearly alike. Mated 

 together (bow cf by arc 9 ), they give in Fi straight-winged flies which 

 inbred give in F2 9 straight to 7 not-straight {i. e., bow, arc, and bow arc 

 together). 



Depressed wings first appeared (April 191 3) among the males of a 

 culture of black flies. They were mated to their sisters and from 

 subsequent generations both males and females with depressed wings 

 were obtained which gave a pure stock. This new character proved 

 to be another sex-linked recessive. 



LINKAGE OF DEPRESSKD AND BAR. 



Depressed (not-bar) males mated to (not-depressed) bar females gave 

 bar daughters. Two of these were back-crossed singly to depressed 

 males and gave the results shown in table 49. Males and females were 

 not separated, since they should give the same result. 



Table 49.— Pi depressed 9 9 X bar 9 9 . B. C. F, bar 9 X depressed <?&. 



