A PHYSIOLOGICAL CHARACTER. 



55 



With Line 711, as well as with most of the other lines, the courses 

 of the curves for the two strains illustrate the marked effect of 

 environmental influences upon reaction-time (figure 5). 



Line 713. 



The data for Line 713 are shown in tables 19 and 20 and in 

 figure 6. Scarcely more than a glance at figure 6 is necessary to 

 convince one that with Line 713 there was no effect of selection, 

 though the selection data for the last year period are suggestive of a 

 possible selective effect. Environmental influences were obviously 

 at play in directing the general course of the curves, which follow 

 each other in an interesting way. The curve for the plus strain is 

 quite irregular, while that for the minus strain is surprisingly free 

 from large minor fluctuations. 



600 



450 



300 



150 - 



4-5 8-9 12-1 4-5 8-9 )2-1 A-5 8-9 12-1 4-5 



1912 1913 1914 1915 



OO^ 



Figure 6. — Line 713. Reaction-time curves. 



For the first 4 months the means for the two strains were 

 476.7 and 459.7 seconds (table 19). The difference is +17.0±37.5 

 seconds. There were 3 very small same-day broods for each strain, 

 with the average for the plus strain 53 seconds the larger (table 18). 

 The large upshoot in the curve for the plus strain for June- July is 

 from an average obtained from a very small number of individuals. 



The data for the year, August 1912- July 1913, show these 

 means for the plus and minus strains: 244.6 and 285.4 seconds. The 

 difference is —40.8 ±11.5 seconds, 3.55 times the probable error. 

 The 14 same-day broods for this period have as averages 233.7 and 

 321.9 seconds, the minus-strain average being larger by 88 ±17.31 

 seconds. The extremely fluctuating course of the curves for this 

 year-period indicates that the differences obtained are not due to 

 an effect of selection. 



During the next year, August 1913-July 1914, the plus mean 

 is higher by 27.0 ±13.89 seconds. (The plus mean is 431.3 seconds 

 and the minus mean 404.3 seconds.) The 7 same-day broods averaged 



