SEX-LINKED INHERITANCE IN DROSOPHILA 163 



are found variations knowTi as black body and vestigial wings 

 respectively, together with some thirty-five other variations. 

 In Group III are found the variations known as pitik eye, 

 spread wings, and ebony body, together with some twenty 

 other variations. In Group IV are included as yet only 

 two characters, bent wings and eyeless, which however show 

 linkage with each other. No inherited characters have been 

 discovered in Drosophila which are not inherited in one or 

 another of the four linkage groups. 



