PARTHENOGENETIC PURE LINE OF APHIS AVEN/E FAB. 69 



35 36 



Selections Made for Shortening the Length of the Antennce in 

 Comparison with that of the Body. Isolation No. 8. 



In isolation No. 8 selection was made in the reverse direction 

 from that of isolation No. 7, using the same character, i. e., the 

 length of the antennae in comparison with 

 the length of the body. Only two selec- 

 tions were made, but the fraternal means for 

 both generations showed that the average 

 length of the antennae was greater than in 

 the fraternity from which the first selec- 

 tion was made, thus showing no inheritance 

 of this fluctuating character. The results 

 for isolation 8 are further explained in Fig. 

 5 and Table V. 



Selections Made in an Attempt to Increase the 20% 

 Length of the Cornicles in Comparison 

 with that of the Body. Isola- 

 tion No. Q. 



When selections were made in isolation 

 No. 3 to increase the absolute length of 

 the cornicles, two variable characters were 

 involved. One of these was a partial 

 variation, and the other an individual 

 variation. In isolation No. 9, selections 

 were made in attempting to increase the 

 length of the cornicles in comparison with 

 the length of the body, a simple partial 

 variable. Only three selections were made 

 in this case which gave the following means 

 (which show the ratio of the cornicle- 

 lengths in percentage terms of the body 

 lengths): 21.12 per cent., 16.86 per cent., 

 and 21.09 P er cent. The first and the last 

 of these means are considerably above the 

 ratio for the stem progenitor of the subline 

 which was 18.8 per cent. The second fraternal mean was much 

 below the ratio for this stem progenitor. 



FIG. 6. Plot show- 

 ing results of selection 

 in isolation No. 9, where 

 an attempt was made to 

 increase the length of 

 the cornicles in com- 

 parison with that ol the 

 body. The lengths of 

 the cornicles expressed 

 in percentage terms of 

 the body length are 

 found in the column of 

 figures to the left. 



