A PHYSIOLOGICAL CHARACTER. 



81 



lines (29 months), representing 95 generations in the plus and 91 

 generations in the minus strain. The data are given in tables 37 

 and 38 and figure 13. 



The courses of the reaction-time curves are extremely irregular, 

 although in a general way the curves follow each other in a manner 

 to suggest environmental influence upon reaction-time. It is obvious 

 that there was no effect of selection. 



The mean reaction-times for the first longer period (8 months) 

 of the experiment were 555.5 and 604.8 seconds, the plus strain 

 being the more reactive by a margin of 49.3 ±14.9 seconds, a differ- 

 ence 3.31 times the probable error (table 37). The 7 same-day 

 broods for this period gave averages indicating greater reactiveness 

 for the minus strain by a difference of 4-111 ±36.23 seconds, more 

 than double the difference obtained from the entire data for this 

 period and in the reverse direction (table 38). 



