The location of notch in the X chromosome was not determined by Dexter, but the mutant has appeared anew three or four times and the position has been found by Bridges to be approximately at 2.6. { 66}
Several mutations have appeared in which the wings 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 chromosome), 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. These 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 different mutations is at once shown on crossing any two, when wild-type offspring are produced. For instance, bow and arc are the two most nearly alike. Mated together (bow [male] by arc [female]), they give in F_1 straight-winged flies which inbred give in F_2 9 straight to 7 not-straight (_i.e._, bow, arc, and bow arc together).
Depressed wings first appeared (April 1913) 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.
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.