412 



WILLIAM L. DOLLEY, JR. 



head, only, was illuminated. Any movement of the legs of the 

 insect could, however, be instantly detected, for, as the legs 

 moved the head was 'bobbed' simultaneously up and down. 

 Thus, by observing the reflected shadow of the head, the periods 

 of activity of the animal could be ascertained. 



The results obtained were essentially the same in all of the 

 seven experiments performed. They may be illustrated by the 

 following detailed description of part of one of them. After the 



Fig. 20 Diagram to show apparatus used in experiments in which the butterfly 

 is suspended above a rotating disk. ,4, Nernst glower; B, disc; C, butterfly; 

 D, holder clamped over wings of butterfly; E, mirror. 



butterfly was placed in the mechanical holder, with the right 

 eye illuminated by the beam of light, it remained quiet for 390 

 seconds; then became active and continued to move for 15 

 seconds; after which periods of rest and activity alternated as 

 follows: quiet 240 — active 10 — quiet 60 — active 30 — quiet 60 — 

 active 5 — quiet 60 — active 30 — quiet 90 — active 5 — quiet 60 — 

 active 120. Whenever the insects were active they attempted 



