376 



GENES MODIFYING NOTCH. 



CLASSIFICATION OF TYPES OF NOTCH. 



In the preceding crosses between short Notch and other races, I was 

 handicapped by the difficulty of giving a more exact classification of 

 the types called atavistic, intermediate, and "short" Notch. In order 

 to get a more objective classification three characteristic flies were 

 picked out from the short-Notch stock (that had been inbred for at 

 least 25 generations, although not in pairs), and drawn (fig. 98, a, h, c). 



Fig. 98. 



The left-hand figure, a, corresponds to the type called intermediate in 

 hybrid Notch flies; the second, b, is a common type somewhat shorter 

 than the last and in crosses would ordinarily be placed with the next 

 type, c. This type is the predominating type in "good" short-Notch 

 stock. 



In contrast to type a, the type called atavistic is shown in figure 94, h. 

 These two types overlap, but in a given case one or the other type is 

 found in the great majority of individuals. 



