PARTHENOGENETIC PURE LINE OF APHIS AVEN.E FAB. 59 



every instance the individual selected for carrying on the strain 

 had the longest cornicles of any in its fraternity, and in all in- 

 stances its cornicles were much longer than the mean obtained 

 for the fraternity. The fraternal means obtained run as follows 1 



15 



16 



17 



FIG. i. Graph, or curve, showing the results of selections made in isolation 

 No. 3 in an attempt to increase the length of the cornicles. The heavy middle 

 line joining the large black dots shows the fluctuations of the fraternal means. 

 The light lines show the fluctuations of the extremes of the different fraternities. 

 The arrows show the amount of regression or digression in each case. 



beginning with the mean for the 315 generation and fraternity: 

 3.058; 2.979; 2.847; 3-26o; 3.463; 3.475; 3.387; 3.510; 3.276; 

 3.321; 3.083; 3.250. The more complete data obtained for 

 isolation 3 are found in tabular form in Table I. 2 



1 In the selection work in this isolation an artificial standard of measurement 

 was employed throughout. The number refers to the divisions of the eye microm- 

 eter, and they were not reduced to the metric scale. In the subsequent isolations 

 all measurements have been reduced to millimeters, unless specifically stated other- 

 wise. 



2 The computations involved in the preparation of the data in this table and in 

 those which follow were made for the first time by the writer, and were also made 

 later by a student in order to get a check on the results. 



