eeq^ctationt 



Fig. 141. Results of selection for a reduced number of bristles continued for 64 generations among 

 the inbred descendants of a single pair of flies. The heavy line shows the percentage of flies with- 

 out bristles in each generation. Note that little change occurs after the 17th inbred generation. 

 (After Payne.) 



g ^nc r « t t Pa« 



Fig. 142. Results of selection for an increased number of bristles made throughout 60 inbred gene- 

 rations upon the same initial stock as is mentioned in the description of Fig. 141. The heavy line 

 shows the percentage of four-bristled (normal) flics in each generation. Note the progressive 

 increase which continued as late as generation 55. (After Payne.) 



