C. H. TURNER. 



this crayfish, when moving on the checkerboard plate, is largely 

 directed by the nearest body of water. It acts as though it 

 were positively hydrotropic. 



TABLE III. 



THE CRAYFISH [Cambarus (Faxonius) propinquits Girard]. 



In an infinite series of experiments, 12.5 per cent, of move- 

 ments toward the position of the sun would indicate that bright- 

 ness of the surrounding region (the direct rays of the sun did not 

 have access to the specimens) did not have a directive effect. 

 The experiments yielded only 6.7 per cent, of movements to- 

 ward the position of the sun. Four individuals made zero per 

 cent, of movements toward the position of the sun, three less 

 than four per cent., in only four cases did the per cent, become 

 more than twelve. Evidently, on the checkerboard plate, the 

 crayfish shows a tendency to move away from tin- brightest part 

 of the lidd. 



In an infinite series of experiments 12.5 per cent, of movements 

 in the direction the head originally pointed would indicate that 

 the position of the head had not intluenced the movements. 



