So 



WALTER E. CARREY. 



In Fig. I the rectangle represents the face of the aquarium ; 

 the large arrows indicate the direction of the stimulating object, 

 and the smaller arrows represent the fish, showing their orienta- 

 tion and direction of movement. 



It makes no difference whether the moving object is anterior 

 to the fish (A) or posterior (B), their orientation is the same. In 

 the former case they move parallel too and toward the object, in 

 the latter case away from it. 



By getting above the aquarium it was determined that the 

 fish react in the same way to objects moving in that plane. 



FIG. i. 



i 



i 



FIG. 2. 



FIG. 3. 



A flounder was introduced into the aquarium and swimming 

 on the bottom beneath the sticklebacks produced the character- 

 istic reflex. 



Almost any variation of these movements may be induced by 

 appropriate movement of the stimulating object, for example the 

 fish can be driven from the upper right hand corner to the lower 

 left hand corner by moving the object in the opposite direction. 



By moving the object in a vertical direction the normal hori- 

 zontal path can be changed up or down at will and it makes no 

 difference whether the stimulating object is anterior or posterior to 

 the fish. Figs. 2 and 3 show the deviation of the horizontal path. 



If the stimulating object be moved slowly in this experiment 

 the path is changed deliberately, but when the stimulus is rapid 

 the fish may shoot in the new direction with great alacrity. A 

 horizontal movement above the fish and at right angles to their 

 long axes results in a deviation of their course, either to the right 



