220 INTELLIGENCE IN LOWER VERTEBRATES 



became convinced that his efforts were fruitless and they 

 were given up. The glass partition was then taken away. 

 The pike which had come to associate darting at the minnows 

 with bumps on its nose left the minnows unmolested there- 

 after, being apparently unaware of the removal of the im- 

 pediment to catching its prey. The interpretation of the 

 experiment of Mobius was questioned by Bateson, whose 

 experiments on the intelligence of fishes gave in general 

 negative results, but it was confirmed by the investigations of 

 Triplett on the educability of the perch. Triplett used an 

 aquarium divided in the middle by a glass plate; in one com- 

 partment he placed a male and a female perch for a period 

 of thirty minutes three times a week, after which they were 

 removed and fed on worms. Soon after the two perch were 

 put in one compartment some minnows were introduced 

 into the other. The perch immediately began the pursuit 

 and frequently butted their heads against the glass, especially 

 when the minnows drew near. The efforts of the fish, 

 especially the female, were very vigorous, but near the end 

 of the period both had given up the chase. In the next 

 trial the perch vigorously pursued the minnows, but with 

 somewhat less energy than in the first experiment. For a 

 month the behavior of the perch continued much the same. 

 The minnows and perch were then kept in the two parts 

 of the aquarium as in the experiments of Mobius and remained 

 there a week. The perch seldom collided with the partition, 

 although they watched the minnows frequently. When 

 angle worms were placed on the other side of the partition 

 the perch dashed violently against the glass for some time 

 in their efforts to reach them. They had learned to avoid the 

 minnows, but the suggestion aroused by the worms on which 

 they were regularly fed proved too strong for them. After 

 the perch had ceased their futile efforts to catch the minnows 



