A PHYSIOLOGICAL CHARACTER. 



99 



time of 135.0 21. 74 seconds. Because of the smaller total 

 numbers of individuals of the same-day broods, the statistical prob- 

 able error was relatively large, but the difference was still 6.31 times 

 the probable error. In only one of these same-day broods was the 

 reaction-time for the brood of the minus strain smaller than that 

 for the plus strain. However, during one period, the last two-month 

 period of this year, the minus strain had a reaction-time 132 seconds 

 lower than that for the plus strain. This was a period of rather 



TABLE 44. Selection data summarized by two-month periods for Line 757 minus. 



severe losses by death in both strains and particularly in the plus 

 strain. In general, however, there has been no obvious relation 

 between losses by death and reaction-time, and it is doubtful if that 

 was an influence at this time. 



The test series conducted during September of this year-period 

 contained 14 broods of each strain, 322 individuals of the plus strain 

 and 367 individuals of the minus strain. The means were 409.0 

 seconds for the plus strain and 859.7 seconds for the minus strain 

 (table 45). Thus the mean for the minus strain was more than twice 

 that for the plus strain. The difference ( 450. 7 12.49 seconds) 



