68 S. J. HOLMES 



insect could only produce a limited movement of the body, but 

 no movement of the head. The wooden L was then clamped 

 upon an iron frame so as to bring the insect in a horizontal posi- 

 tion, and the feet of the insect were allowed to rest upon a light, 

 horizontal disk capable of easy rotation. Thtf light employed 

 rested upon a firm stand so that no complication could arise 

 from that source. Care was taken to see that the glue was 

 firmly set and that the head made no motions during the strug- 

 gles of the insect. Everything was made as rigid as could well 

 be, so that one could be assured that eye and light must remain 

 in a constant relation, however much the insect might move 

 its legs or even its body. 



Under these conditions, which would seem to insure the con- 

 stant stimulating influence of light, how did the butterflies 

 react? Specimens of Vanessa caryce were chosen for experi- 

 mentation since they were easily obtainable. The first individual 

 selected was found to rotate the disk quite consistently away 

 from the light. When the light was placed on the other side 

 of the insect the disk was rotated in the reverse direction. Fre- 

 quently the movements of the insect were soon discontinued, 

 but when the foot or body was touched with a needle the rotation 

 of the disk was generally resumed. The light was changed 

 from one side of the insect to the other fifteen times and each 

 time the disk was unmistakably rotated away from the light. 

 After a rest in the dark for about an hour the light was changed 

 from side to side twelve times with the same result as before. 

 The insect which now gave evidence of exhaustion was liberated; 

 the glue fastening its head to the apparatus was found to be 

 well hardened. 



Other butterflies of the same species were experimented with 

 in the same manner and gave results equally decided. The 

 responses of the butterflies were not quite so vigorous as in the 

 experiments originally described. This is probably due to the 

 unnatural stimulation caused by the head being firmly glued to 

 a foreign object, and also to confinement in a fixed position 

 during the time the glue was being dried. Nevertheless the 

 results made it abundantly evident that the butterflies with the 



