210 'Journal of Comparative Neurology a^id Psychology. 



not, in this instance, "select" the region of greater light-intensity 

 because of the intensity /^^rj--?, but because they became imprisoned 

 in it through orientation as a result of the directive stimulus. It 

 is only through rays which strike the larvae directly from above 

 or from below that an approximately non-directive influence can 

 be obtained. 



Fig. 2. 



Fig. 3. 



Fig. 



Figs. 2 and 3 show the orientation of the lan'ae in tubes standing in the vertical position; Fig. 4, in 

 the_horizontal. The arrows represent the direction of the light rays striking the tubes from the side. 

 The'cross hatching represents the parts of the tubes covered with black paper. 



Experiment 2. Reaction to intensity of light — In this experi- 

 ment use was made of the glass-bottomed box A with the light- 

 shaft, and the colored-glass plates or graded light screens. First 

 the glass plates were arranged over the top of the light-shaft in the 

 order blue, green, orange, red. The box was filled with salt water 

 to a depth of 15 mm., and ten first-stage larvae were placed therein. 

 The light-tight cover was then put in place and the larvae were 

 allowed five or more minutes to become acquainted with their new 

 environment. The result was as follows: 



