THE CUNNING OF TROUJ 63 



to get the better of its inherited instincts, if some 

 disagreeable result follows the attempt to gratify 

 them. Present one with a fly dipped in an un- 

 pleasantly tasting substance like turpentine, and 

 after two trials it will learn to subordinate the 

 whole teaching of its countless ancestors that a 

 fly within reach is a thing to be pounced upon. 

 But a fish will go on plunging at a thing which, 

 were it a teachable creature, experience would have 

 warned it to leave alone. There are countless 

 examples of salmon, and even trout, taking the 

 fly within a few minutes of being struck, and 

 there are many cases of a salmon being caught 

 with the hook still in its jaw which it had broken 

 off after a mighty struggle half an hour before. 

 But more striking experiments than these have 

 attested the unteachableness of fish. Mr. Bateson 

 tells how none of the fish in his aquarium seemed 

 to get a lasting appreciation of the nature of the 

 glass wall of the tank. The same fish again 

 and again knocked their heads against the glass in 

 trying to seize objects moving on the other side, 

 and some of the oldest inhabitants continued to 

 the last subject to the fish's natural instinct to 

 pounce, though it meant a damaged snout every 

 time. Even the examples of teachableness in fish 

 only emphasize a general belief in their unteach- 

 ableness, as in the well-known case of the pike 

 which dashed itself for three months against a 

 glass partition in the attempt to get at some 

 minnows in the next division of the aquarium, and 

 became at last so firmly persuaded of the danger 

 of attacking them that, when the partition was 



