REACTIONS TO LIGHT IN VANESSA ANTIOPA 405 



light was reduced to 2 mc. The higher intensity was produced 

 by replacing the 16 c.p. lamp with two Nernst filaments side by 

 side. The luminous intensity produced in this way was 460 

 mc. The insects were tested first in the light of low intensity, 

 and then in that of high intensity. They were kept in darkness 

 for twenty minutes before being exposed to either of these two 

 lights. In the second experiment a white sheet of paper measur- 

 ing 20 X 17 cm. fastened over a piece of board of the same size, 

 was placed above the center of the box at an angle of forty-five 

 degrees with the plane of the bottom. A horizontal beam of 

 light from a Nernst glower was thrown on this sheet of paper, 

 and reflected into the box below. By altering the elevation of 

 the reflecting surface, and also by varying the distance between 

 the glower and this surface, the intensity of the light in the box 

 could, be changed. In this way light of very low intensity was 

 produced. 



The results obtained in these experiments may be illustrated 

 by a description of the behavior of two animals. 



Butterfly, iO/13-a (left eye blackened), after having been in 

 darkness twenty minutes, was exposed to non-directive light of 

 an intensity of 2 mc. It made four circus movements, turning 

 continuously toward the functional eye, and then stopped. It 

 was picked up and dropped a second time, on the smoked papers 

 in the bottom of tlie box. In this, the second trial, it again per- 

 formed circus movements in the same direction. Similar reac- 

 tions were observed in all the rest of the ten trials made (fig. 18). 

 After a stay of twenty minutes in darkness, the source of light 

 of high intensity was used, and the insect was given ten trials. 

 In all of these it either made circus movements in the same direc- 

 tion as in the lower intensity, with a much smaller degree of 

 curvature, or walked in fairly straight courses, as is shown in 

 figure 19. 



Instead of moving in smaller 'circles* in light of high intensity 

 than in that of low intensity, as the 'continuous action theory' 

 demands, the organism showed the reverse behavior, for the 

 smaller 'circles' were all made in the lower intensity instead of in 

 the higher. 



