RELATIVE STIMULATING EFFICIENCY OF LIGHT 



171 



light of a flash-frequency of 30 per second, which has been 

 shown to have a great stimulating effect upon this specimen 

 of Vanessa, causing movement toward the source of intermittent 

 light. The butterfly for 10 trials had reacted to this light from 

 this direction, and then when the conditions were changed the 



FIG. 8. Paths made by a specimen of Vanessa (butterfly 20) showing the effect 

 of previous experience on its reactions in a field of light composed of two hori- 

 zontal beams at right angles with each other. (Reduced by three fourths). Ar- 

 rows to the left in A and in B, direction of rays of intermittent light. Arrows be- 

 low in A and in B, direction of rays of continuous light. Illumination in each 

 beam in A and B, 10.5 m.c. Arrows to left in C, direction of rays of continuous 

 light, illumination, 14 m.c. ; arrows below in C, direction of rays of continuous 

 light, illumination, 10.5 m.c. Intermittent light of flash-frequency of 2 and 10 

 per second in A and in B, respectively, produced by disk with three-fourths re- 

 moved. Figures with prefixed signs have the same significance as in figure 7. 

 While the animal was making trails marked X in A and in B the conditions were 

 not the same as in the other trials in A and in B. During these two trials a beam 

 of continuous light was substituted for the beam of intermittent light, thus 

 changing the conditions to those which were present in C. Trails X were tenth 

 in each series. Note that although the conditions were different, about the same 

 angles were made in trails X as in the other trails in A and in B. Note also that 

 in making trails X the insect was reacting in part to light conditions which had 

 ceased to exist. In C are reproduced other trails made by this butterfly under 

 exactly the same light conditions as those in which trails X were made. 





