PROBLEM OF SEXUAL SELECTION IN DROSOPHILA 363 



(1) White eyes. This form was first described by Morgan 

 ('10). There is no color in the eye. This probably means that 

 the fly is blind, and it has often been observed to be less strongly 

 phototactic than the wild fly. White eyed flies are also less 

 active and vigorous than normals. 



(2) Yellow body color. Described by Morgan ('11). The 

 whole body of this fly is lighter than that of the normals, and 

 there is a distinct yellow color to the wings. Sight seems to be 

 normal, but again the flies are not so active as are the normals. 



(3) Curved wings. The main interest of this form in this 

 connection is that the wings are always held extended, in some- 

 what the same position as that of the courting males. The 

 flies are perhaps a little less active than the normals 



(4) Vermilion eyes. Described first by Morgan ('11a). These 

 flies differ from the normals in that the eyes are of a brighter 

 and less intense red. Their vigor and activity is very little, if 

 at all, inferior to that of the normals. 



Some of the flies used had yellow bodies and white eyes, 

 and in one experiment a few vermilion eyed yellow black col- 

 ored females were used. This latter combination was at the 

 time considered one of the weakest stocks in the laboratory, 

 and was used for that reason. 



The method of the experiment was as described above for the 

 wing clipping experiment. For instance, a white eyed female 

 would be given her choice between a red male and a white one 

 of the same age and size. Then the experimenter simply watched 

 until pairing was seen, and the flies were then thrown away. 

 The following table (IV) gives the results obtained. 



J White d 19 



