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 Mébius 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 Mébius andremained 
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 
