172 WILLIAM L. DOLLEY, JR. 



insect continued to behave as it had just been doing. It deflected 

 in the same direction. It was not reacting to the conditions 

 which existed at that moment, but it was reacting to stimuli 

 which had ceased to exist. This is probably an example of 

 organic memory. This conclusion is confirmed by tests on 

 another butterfly which are presented in figure 8. 



This insect (fig. 8, C) was given 10 trials in two beams of 

 continuous light, the illumination in one being 14 m.c. and that 

 in the other 10.5 m.c. The angles made by the paths ranged 

 from +4 to +20 degrees. It was then given 9 trials in two 

 beams of equal illumination, 10.5 m.c., one of continuous and 

 the other of intermittent light of a flash-frequency of 10 per second 

 produced by a disk with three-fourths removed (fig. 8, B). 

 The angles made by these paths ranged from +17 to +39 degrees. 

 Suddenly the light conditions were changed so that they were 

 the same as those in which the previous 10 trials had been made. 

 The tenth trial was then given in these conditions (both beams 

 of continuous light). The angle made was +32 degrees, an 

 angle very nearly like those that had just been made under dif- 

 ferent light conditions and very unlike the angles that had 

 previously been made under similar conditions. It is probable 

 that in making this tenth trial the insect was reacting to light 

 conditions that had ceased to exist. Its behavior was influenced 

 still by its previous experience. If this is true it must be con- 

 cluded that the orientation of Vanessa in light from two hori- 

 zontal beams which cross at right angles depends upon its 

 previous experience. 



VIII. SUMMARY 



1. When Vanessa antiopa is exposed to continuous light from 

 two sources, the rays of which cross at right angles, it moves 

 toward a point between the sources. The location of this point 

 depends on the relation between the illumination received from 

 the two sources. 



2. The stimulating efficiency of intermittent light in the 

 orientation of Vanessa varies with the flash-frequency. At 

 flash-frequencies of 20 and 30 per. second it is higher than that 



