8o Instinct and Intelligence 



feet habit in 250 experiments. The glass plate 

 was then shifted to the other passage, and the 

 crayfish was naturally completely baffled for a 

 time, but ultimately succeeded in learning the 

 new habit." 1 



From these and similar experiments it is 

 evident the functions performed by the nervous 

 matter constituting the lines of communication 

 between sensory organs, nerve centres, and their 

 efferent fibres improve by use. Thus the pur- 

 posive movements of the crayfish, after the 

 animal had been subjected for a number of 

 times to the same form of stimulus, became so 

 perfect that other less energetic stimuli failed 

 at the moment to elicit a response, or to influence 

 the behaviour of the animal. Movements ot 

 this kind are often ascribed to experience 

 gained by the animal during repeated trials to 

 attain desired or pleasurable ends. Mr. 

 Romanes was of opinion that we can only infer 

 intelligence in an animal when we see the 

 individual profit by his own experience. But 

 what is the meaning to be attached to the terms 

 experience and intelligence? Behaviour, when 



1 The Animal Mind, by M. F. Washburn, pp. 220, 319, 323. 



