164 THE SOCIAL LIFE OF ANIMALS 



The fish were placed in the central space and those 

 in half the tanks were trained to come forward as 

 usual. In the other half, two selected fish were con- 

 ditioned to come forward and two were similarly 



A ^ 



V 



Fig. 34. The aquarium-maze used in training part of 

 the fish to come forward and part to go to the rear to 

 be fed. (From Welty.) 



trained to move to the rear compartment to be fed. 

 The experiment was tried several times with gold- 

 fish, the minnow, Fundulus, common at Woods Hole, 

 and another marine minnow, Cyprinodon. For one 

 reason or another, only one series in which the fish 

 were comparable was successfully completed. The re- 

 sults are shown in Figure 35. Generally speaking, 

 the cohering groups of Cyprinodon learned more 

 rapidly and reacted more steadily than the separat- 

 ing groups. This, then, is one factor that is working, 



