E. Hindle and G. Merriman 
207 
In this diagram the top arrow represents the direction of the 
horizontal rays of light which acted during the whole experiment. In 
addition below the line XY the paper was brilliantly illuminated from 
above. Five ticks A, B, C, D, E, were placed on the paper and allowed 
to walk freely in any direction. In this case they all walked directly 
away from the source of light until they reached the area of bright 
illumination from above {XY). In every case the tick retreated, in 
Direction of Horizoniat 
I Rays of Lijht . 
A BODE 
Diagram 2. 
opposition to the action of the horizontal rays, and endeavoured to 
avoid the region of brilliant illumination. In only one case {E) did the 
tick after coming into the region for a second time, attempt to cross it, 
and shortly after its entrance the action of the horizontal rays again 
became apparent. In every other case the ticks skirted along the edge 
of the illuminated area and would not enter it. 
