LINKAGE GROUPS 



97 



In the seventh figure {g) the wings are beaded, 

 i.e., the margin is defective at intervals, giving a 

 beaded-Hke outhne to the wings. This condition is 

 very variable and much affected by other factors 

 that influence the shape of the wings. 



There are many eye colors in this Group — one of 





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Fig. 43. — Some of the characters of the third chromo- 

 some of Drosophila melanngaster. S€e text. 



these, sepia, becomes very dark in old flies. Pink and 

 peach eye colors are modifications of the same gene 

 (a case of multiple allelomorphs). Two other eye 

 colors in this group, scarlet and cardinal, are almost 

 indistinguishable, but the genes for these characters 

 lie in quite different parts of the chromosome. 



