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A. M. Banta 



14 hours before the experiment with hght began, whereas in the 

 former case they had been in the tank only five minutes. More- 

 over, in the case recorded in Table VIII the light was transferred 

 from one end of the tank to the other during the course of the 

 experiment in order further to test the efficiency of the light as a 

 directive influence. 



Since the animals, before this experiment began, had been in 

 the tank over night, the thigmotactic or other disturbing influences 

 due to their transference to the tank was eliminated. The pho- 

 tokinetic effect was therefore easily recognizable. It appeared 

 within a few minutes after the exposure to light began and con- 



