LINKAGE GROUPS 91 



111 the six flies drawn in figure 40 there are sliown 

 five different wing characters. The first of these 

 types (a) is called cut, because the ends of the wings 

 look as though they had been cut to a point. The an- 

 tennae are displaced downward and appressed and 

 their bristle-like aristae are crumpled. 



The second figure (h) represents a fly with a 

 notch in the ends of the wings. This character is 

 dominant, but the same factor that produces the 

 notch in the wings is also a recessive lethal factor; 

 because of this latter effect of the character, no males 

 of this race exist, and the females of the race are 

 never pure but hybrid. This same figure (b) is used 

 here to show two other sex-linked characters. The 



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Fig. 40. — Some of the charaeters of the first chromo- 

 some of Drosophila melanogaster. See text. 



