THE LINKAGE OF TWO FACTORS IN DROSOPHILA. 



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In previous papers on Drosophila a large amount of data has 

 been given showing that in regard to any sex-linked factor, the, 

 yellow factor, Y, follows Mendel's law of independent segregation ; 

 in other words, the yellow factor segregates independently of all 



2. 



3 



5 6 4 



FIG. B. 



sex-linked factors. The fact that wingless flies do not show 

 sex-linked inheritance has also been reported, but the character 

 of the wing itself and its mode of origin have not been fully 

 described. 



The size in relation to the body, and general character of the 

 wings are shown in Fig. A. They are little more than scales held 



