HEREDITY OF BODY COLOR IN DROSOPHILA 29 



brownish 3'ellow. There are no dark bands along the sides of 

 the veins. The upper surface of the head of the wild fly, and 

 also of the mutants is colored like the thorax. The under surface 

 of the abdomen is more yellow in the male, than in the female. 



The yelloiv fly. The upper surface of the thorax is yellow 

 ochre in color and lighter than that of the wild fly. It is inter- 

 esting to observe that the dark marking or shield is always 

 absent from the yellow flies. 



The light bands on the abdomen are of the same color as the 

 thorax, i. e., pure yellow ochre, and lighter than those of the 

 wild fly. The dark bands are brown. The legs are the same 

 color as the thorax. The veins of the wings are yellow like the 

 thorax. The interspaces (or background) are of a transparent 

 golden yellow and strongly contrast with the color of the 

 wings of the wild fly. The hairs are brown, instead of black 

 as in the wild fly. 



The black fly. The upper surface of the thorax is the same 

 general color as that of the wild fly, but darker in the sense of 

 being browner. The black trident is always present and con- 

 spicuous, and the two lateral mai kings are also conspicuous. 

 The trident is not only well developed, but appears to be longer 

 and narrower than that of the normal. It is one of the most 

 striking features of the black mutant. The light bands of the 

 abdomen are darker than those of the normal, but not so dark 

 as is the thorax. The dark bands are very black. The legs 

 are blacker than the legs of the wild fly, especially the more 

 distal parts. The hairs on the body are black. The veins of 

 the wings are very black. On each side of each vein there is 

 a dark (semitransparent) band. The interspaces between these 

 bands are gray, but darker than the gray of the wing of the wild 

 fly. While the black fly is blacker than the wild fly in nearly all 

 of its parts, so that a heap of them is very dark compared with 

 a heap of the normal flies, the most striking character that dis- 

 tinguishes them from the other types is the dark wings with 

 the dark bands on the sides of the veins. 



The broivn fly. The upper surface of the thorax is brown. 

 The brown color deepens as the fly gets older, and the color 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 13, NO. 1 



