RELATIVE STIMULATING EFFICIENCY OF LIGHT 



155 



deflected more toward the source of intermittent light of this 

 flash-frequency than they did toward either source when tested 

 in two beams of continuous light of equal illumination. More- 

 over, the average angle of deflection of all 10 insects in light of 30 

 flashes per second (+8.98 degrees) was greater than that made 

 in continuous light. 



The efficiency of light of 100 flashes per second is apparently 

 equal to that of continuous light for the average angle of deflec- 



TABLE 4 



Relative stimulating efficiency of intermittent light of various flash-frequencies and 

 continuous light of equal illumination. This table is based upon the data given 

 in table 5 



tion of all 10 insects made in both sorts of light was approxi- 

 mately equal, being +6.61 degrees in the former and +5.84 

 degrees in the latter. This conclusion is supported by the fact 

 that 50 per cent of the 10 animals deflected more toward the 

 source of intermittent light than they deflected toward either 

 source when tested in two beams of continuous light of equal il- 

 lumination. Forty per cent deflected less, and 10 per cent de- 

 flected to an equal extent. It is therefore evident that for 

 Vanessa the stimulating efficiency of intermittent light of a flash- 

 frequency of 100 per second is approximately equal to that of 

 continuous light. 



A study of table 4 indicates that the same conclusion is to be 

 drawn as to the stimulating efficiency of intermittent light of 



