Description of Characters. 17 



Singed (si). (Figure 4.) 



Description. — Singed affects the bristles and hairs, particularly on the body and 

 legs. The bristles are shortened and depressed and are twisted and curled, as if 

 singed. The hairs are likewise depressed and sometimes curled. The hairs in the 

 wings are affected slightly, if at all. Those on the costa lie in approximately a normal 

 position, instead of standing out at an angle from the wing, as they tend to do in 

 forked flies. The eggs and the body-color are normal, or very near normal. The 

 character is ordinarily used as a recessive, and is the same in males and in homo- 

 zygous females. It is possible to distinguish heterozygous females from the wild type, 

 however, by their shorter, less tapering bristles. Singed flies have good viability, 

 and both sexes are fertile, making the character one of the most useful for linkage 

 studies. 



Origin. — (P. 220.) A single male was obtained from glazed stock. 



Comparison. — (See page 60.) 



Hairy (ha). 



Description. — Superficially hairy resembles "rugose," but it lacks the light color 

 of the latter and has a sprinkling of heavy black hairs over the eye-surface, giving it 

 a peculiar bushy appearance entirely wanting in rugose. Typical specimens of 

 hairy are readily recognized, but the character varies considerably and is not always 

 readily distinguished. The stock was discarded after a few linkage experiments were 

 completed. 



Origin. — (V 745.) One male was found among the offspring of a single pair. 

 (See Metz, 1918, p. 60.) 



Magenta (m). (Plate 1, Figure 7.) 



Description. — Magenta is very similar to sepia, but is slightly more reddish in 

 tone and is a "deeper" or more "liquid" color instead of being "flat," as in the case 

 of sepia. The character is more marked in the males than in the females, but is 

 usually readily recognizable in either sex. It is almost, if not quite, indistignuishable 

 from the third chromosome dominant "garnet." The viability of magenta flies is 

 excellent and the character is one of the best for linkage studies. 



Origin. — Magenta was first observed in half of the sons of an "acute" female. 

 (Metz, 1918, p. 599.) 



Comparison. — Magenta suggests "garnet" in D. melanogasfer and "carmine" in 

 D. simulans. 



Forked (f). (Plate 1, Figure 3.) 



Description. — In forked flies the bristles on the head, thorax, and legs are shorter 

 and stouter than usual, are often irregularly twisted, or bent at sharp angles, and a 

 few are usually forked. The hairs are not greatly affected, but are somewhat stouter 

 and less tapering than usual. The thorax is darkened and has a characteristic 

 glossy appearance. Males and homozygous females are similar; heterozygous females, 

 like those of singed, have the bristles slightly shortened. The eggs appear to be 

 normal. 



Forked resembles singed in its affect on the bristles and hairs, but is much less 

 extreme than the latter. The bristles and hairs are not flattened do\vn or tightly 

 twisted as in singed. On the legs they are only slightly affected in forked, while 

 they are markedly affected in singed flies. The marginal hairs on the costal vein of 

 the wing stand out at a greater angle than usual, especially toward the back of the 

 wing. 



In singed the hairs on the abdomen are twisted and depressed, while in forked 

 they are almost normal. In the double recessive forked-singed males the hairs and 



