BEHAVIOR AGREEMENT AMONG ANIMALS. 



309 



FIG. 35. Shows the light grader in which the experiments were performed. It 

 is in all essentials like that described by Mast fn), p. 61. A 132-watt lamp was 

 used. The heat screen of distilled water, the gradient box and reflecting mirror 

 are shown. 



FIG. 36. Shows the plan of the experiments. The light gradient was focused 

 at the horizontal line and the rays diverged slightly as indicated by the diverging 

 lines. G is the glass plate to confine the animals from the dark corner. .4, B, and 

 C are the positions in which the bottomless cylinder was placed to confine the 

 animals, before readings. The portion of the box to the right of the C was in 

 essential darkness. 



