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they did not react so definitely as the immature stages. Some 
individuals walked directly away from the light, but in a few cases 
for a short distance they approached the source of illumination, 
eventually, however, turning round and walking in the opposite 
direction. The above experiments (a-e) Avere repeated ten times 
Avith similar results in each case. 
/ a. Phototropism, employing artificial light. 
The above series of experiments Avere repeated employing electric 
light as the source of illumination. White, red and yellow lights 
were used, respectively, and the results were practically identical Avith 
those obtained Avith daylight. If anything in these experiments the 
negative phototropism was rather more marked. 
In addition, several attempts Avere made to cover various parts of 
the tick with substances opaque to light, in the hope of ascertaining 
whether the Avhole surface of the tick Avas equally sensitive. Un¬ 
fortunately we were unable to find any method of covering the tick’s 
surface, either in part, or whole, without seriously interfering Avith its 
movements. Therefore it Avas attempted to solve this question by 
exposing the ticks to the action of light coming from two different 
sources at right angles to each other. 
