86 Studies in Animal Behavior 



Stenopelmatus, which is negative to light, was placed 

 in the enclosure after having its left eye blackened 

 over. When crossing the enclosure it invariably 

 turned to the left and continued to go around in 

 that direction when it came in contact with the edge. 

 Several flies showed very decided circus movements 

 toward the normal side. Thus even under condi- 

 tions of practically continuous stimulation these 

 forms kept up their orienting activities. 



In another set of experiments insects were held 

 in a fixed position while their efforts at locomotion 

 were given opportunity for expression by rotating 

 a horizontal disk mounted on a pivot like the turn- 

 table of the microscopist. "The apparatus was made 

 very light and easy running so that even a small 

 insect could set it in motion. By holding an insect 

 over the disk with the head pointing either toward 

 or away from the center, and having a light so that 

 the rays fell on one side of the body, the movements 

 of the legs which would ordinarily turn the insect 

 toward the light would simply cause the disk to ro- 

 tate in the opposite direction. With the insect held 

 steadily, the stimulus afforded by the light would 

 naturally remain constant, and if light oriented by 

 its constant stimulating effect we might expect that 

 the insect would keep rotating the disk in its at- 

 tempts at orientation. 



"Butterflies proved to be very convenient to work 

 with, since by grasping them by the wings folded to- 

 gether above the body they could be held quite 



