A PHYSIOLOGICAL CHARACTER. 



TABLE 11. Selection summary for Line 689. 



47 



Time period. 



Apr.- July 31, 

 1912 



Aug. 1, 1912- 

 July 16, 1913 



(Plus.. 

 I M imu 



Plus. 



9-19 

 9-17 

 20-52 

 18-60 



36 



174 



484** 

 295.1 

 255.1 



260.7 

 69.4 

 194.8 

 145. S 



23.9 

 S3. 7 

 8.2 

 6.6 



S 



+34.2 

 +40.0 



10.5 



0.83 



3.71 



TABLE 12. Same-day broods. Summary of data for Line 689. 



periment with this line in July 1913, the mean for the plus strain 

 was 295.1 seconds and for the minus 255.1 seconds. The difference 

 was +40.0 10. 5 seconds, 3.71 times its probable error. There 

 was only one same-day brood 1 for the four-month period, but there 

 were ten same-day broods during the later year-period. For these 

 same-day broods likewise the reaction-time for the minus strain was 

 lower than for the plus strain, but the difference was only 3 seconds 

 (table 12). 



It is an interesting fact that in this line, in opposition to selec- 

 tion, the minus strain persistently (except for 1 two-month period, 

 see table 10) maintained a lower reaction-time than the plus strain. 

 This difference, while not large for the greater part, is so general 

 that it can scarcely seem to be merely coincidental. The same-day 

 broods (table 12) show the minus broods with a smaller reaction- 

 time, but for the only significant group of these the difference is so 

 slight (3 seconds) as scarcely to be suggestive. 



1 For this pair of very small broods the mean of the plus strain was 163 seconds greater 

 than that for the minus strain. 



