GROUP BEHAVIOR 171 



lows through the clear glass became conditioned in 

 two ways which were not open to the fish behind 

 an opaque glass. In the first place they saw the fish 

 move forward on the reception of a given stimulus, 

 pass through the gate, receive food, and give no evi- 

 dence of an avoiding or "fright" reaction. This prob- 

 ably gave what might be called a certain reassurance. 

 Secondly, they showed group cohesion, and moved 

 forward with the reacting fishes; at times they were 

 even seen to move forward in advance of the fishes 

 on the maze side of the aquarium. 



When transferred to the aquarium-maze and given 

 the releasing stimulus of an increase in light, accom- 

 panied by the opening of the gate, both types of 

 previous experience probably played a role in pro- 

 ducing a faster reaction. Fish behind the opaque 

 glass could have neither of these helpful experi- 

 ences. When their narrow aquarium was flooded 

 with light they ordinarily moved back to the far end 

 and remained there. There was nothing to train 

 them to overcome this normally negative reaction. 

 So reviewed, it must be said that this behavior has 

 some points of resemblance to what is called imita- 

 tion in other animals. 



There is also an element of imitation in the 

 greater food consumption of grouped fishes. One fish 

 sees another pursue, attack and consume a bit of 



