272 



J. M. Banta 



ably a chance result since from about 10:30 a.m. (when the first 

 negative response seemed indicated) to 12:00 the mean average 

 position shifted back and forth, at one time apparently indicating 

 a negative response and at another a positive one. From 12:50 

 to the close of the experiment at 5 .-35 the apparent negative photo- 

 taxis predominated and the other influences became less and less 

 efi^ective. The mean average position during the course of the 

 experiment shifted from 3.77 to 1.77, a movement of 2 in a nega- 

 tive direction. 



Fig. 5 represents the results of the experiment recorded in 

 Table VII. The loci of the curve show the mean average posi- 

 tions of the animals during the course of the experiment at inter- 

 vals which were at first fifteen minutes apart, but later not so 

 close together. 



Table VIII shows the results of an experiment similar to the one 

 last discussed. But in this case the animals had been in the tank 



4. 



3.5 



2,5 



1.5 



Fig. 5. Ca;cidotea stygia (26 individuals); Nov. 7, 1906; previous exposure, diffuse daylight; 

 illumination horizontal, 2855 ^- '^- 



