380 DWIGHT E. MINNICH 



determination have been computed collectively in the manner 

 already described. Single values have thus been derived which 

 express the average deflection, or tendency to turn, exhibited by 

 the animal in each determination. When the turning was chiefly 

 toward the blackened eye, the sign of these values is negative; 

 when chiefly toward the functional eye, it is positive. If, now, 

 the value of each determination in 24 mc. light be subtracted 

 from the corresponding one in 957 mc. Hght, differences will be 

 obtained which should answer conclusively the question of rela- 

 tionship between the amount of turning and the intensity of 

 photic stimulation. 



The differences obtained in the manner just described I shall 

 designate as d. A given value of d may be negative or positive. 

 If it be negative, it signifies one of the two following possibilities : 



1. The bee turned more toward the blackened eye in an illumina- 

 tion of 957 mc. than it did in one of 24 mc. 



For example, in the second pair of determinations on bee no. 

 32 (table 2), 



957 mc. 24 mc. 



-13.287cm. - (-9.227cm.) = -4.067cm. 



2. The bee turned less toward the functional eye in an illumi- 

 nation of 957 mc. than it did in one of 24 mc. 



For example in the second pair of determinations on bee no. 23, 



957 mc. 24 mc. 



+6.447cm. - (+8.927cm.) = -2.48°/cm. 



If, however, the value of d be positive, it signifies one of the 

 two following possibilities : 



1. The bee turned less toward the blackened eye in an illumina- 

 tion of 957 mc. than it did in one of 24- mc. 



For example, in the first pair of determinations on bee no. 31, 

 957 mc. 24 mc. 



-3.877cm. - (-7.147cm.) = +3.277cm. 



2. The bee turned more toward the functional eye in an illumi- 

 nation of 957 mc. than in one of 24- mc. 



