RATE OF LOCOMOTION IN VANESSA ANTIOPA 515 



the other end, and the illumination in the trials in intermittent 

 light was one-half of this. 



In experiment 4 the rate of locomotion in continuous light and 

 in intermittent light of a flash frequency of 16 per second was 

 ascertained. The mode of procedure was exactly that in experi- 

 ment 3 except that one-fourth of the disc was removed during 

 the trials in intermittent light. The illumination in the trials 

 in continuous light ranged from 1500 m.c. to 1.56 m.c. at the two 

 ends of the table. The illumination in the trials in intermittent 

 light was one-third of this. 



The object of experiment 5 was to ascertain the rate of move- 

 ment of Vanessa in intermittent light in which the frequency of 

 interruption was very high and very low. One-half of the disc 

 was removed. An insect was first given one trial in continuous 

 light, then one in intermittent light with a flash frequency of 

 22 per second, then one in intermittent light with a flash fre- 

 quency of 1 per second, and finally one in continuous light with 

 the motor running. This series of four trials was repeated a 

 second time, giving two trials for each insect under each of the 

 four different conditions. The illuminations used were the same 

 as those used in experiment 3. 



The results obtained in these three experiments are presented 

 in tables 4, 5, and 6. 



As is shown in table 4, intermittent light of a flash frequency 

 of 10 per second seems to stimulate Vanessa, since 6 of the 10 

 insects tested moved faster in intermittent light of this frequency 

 than they did in continuous light. Moreover, the average 

 rates of movement of all 10 insects in continuous light and in 

 intermittent hght were 2.67 cm. and 2.78 cm. per second, re- 

 spectively. That vibration from the motor did. not produce 

 this result is proved by the fact that 83 per cent of the insects 

 which walked faster in intermittent light moved slower in con- 

 tinuous light when the motor was allowed to run than they did 

 in continuous light when the motor was not running. The 

 running of the motor therefore seems to retard movement. 



That Vanessa also tends to move faster in intermittent light 

 of a flash frequency of 16 per second than in continuous light is 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 23, NO. 3 



