244 THE WONDER OF LIFE 



at Monaco with a fish called Coris julis, whose intelligence 

 is at an interesting incipient stage. To begin with, he 

 showed that when he disguised the hook very cleverly, he 

 could catch the same fish as often as he pleased. But this 

 only proved that the disguising of the hook was practically 

 perfect, and that the fish was appetized. If there was 

 no hint of the hook, there was nothing which an unreflecting 

 creature could learn. A certain sensory impression raised 

 a recollection of a pleasant experience, and action followed 

 almost like a reflex. 



Oxner's experiments with the sea-perch (Serranus scriba) 

 are very instructive. In an aquarium he hung a red and 

 a green cylinder by silk threads of a similar colour, and 

 put food in the red one only. For the first two days the 

 wary fish did not approach the cylinders at all. On the 

 third day, after fifteen minutes' ' deliberation ', it entered 

 the cylinder and ate the food ; on the fourth day it did 

 this after five minutes ; on the fifth day after half a minute ; 

 from the sixth to the tenth day it rushed in at once. On 

 the eleventh day it entered a fresh red cylinder that had 

 no food in it, and waited there for three minutes. So that 

 one may reasonably conclude that an association had been 

 established between the red colour and the food. 



On each of the succeeding six days the fish rushed into 

 the empty red cylinder, and when Oxner dropped in some 

 food, a little was taken. On the eighteenth, nineteenth and 

 twentieth days, the fish was unappetized and would not 

 eat the food. But the interesting fact was, that even in 

 the absence of appetite, the fish seemed unable to resist 

 rushing into the red cylinder. The association worked 

 almost like a reflex. It may be noted that there is no 

 particular attraction in the red colour, for the same general 



