154 



WILLIAM L. DOLLEY, JR. 



Examination of these shows that the stimulating efficiency of 

 intermittent light of a flash-frequency of 20 per second is higher 

 than that of continuous light. This statement is based on two 

 facts: first, the average angle of deflection of all 10 insects in 

 intermittent light of 20 flashes per second (+7.83 degrees) was 

 greater than that made in continuous light; and second, 80 per 



TABLE 3 



Comparative stimulating efficiency of continuous and intermittent light. The num- 

 bers indicate the degree of deflection from the line bisecting the angle between two 

 beams crossing at right angles. "Plus," deflection toward the source of intermit- 

 tent light, or toward the right if both beams are continuous. "Minus," deflection 

 toward the source of continuous light, or toward the left if both beams are con- 

 tinuous. Each figure given is the average angle of 5 trials 



cent, or 8 out of the 10 insects tested, deflected more toward 

 the source of intermittent light of this flash-frequency than they 

 did toward either source when tested in two beams of continu- 

 ous light of equal illumination. 



Similarly, the stimulating efficiency of intermittent light of a 

 flash-frequency of 30 per second seems to be greater than that of 

 continuous light, for 70 per cent, or 7 out of the 10 insects tested 



