A Note on the Psychology of Fishes 171 



against the screen less and less, swims up and down along it 

 fewer and fewer times, stays still less and less, until finally 

 his only act is to go to the right-hand side, rise up, and 

 swim out. In correspondence with this change in behavior 

 you will find a very marked decrease in the time he takes to 

 escape. The fish has clearly profited by his experience and 

 modified his conduct to suit a situation for which his innate 

 nervous equipment did not definitely provide. He has, in 

 common language, learned to get out. 



This particular experiment was repeated with a number of 

 individuals. Another experiment was made, using three 

 slides, II, III, and another, requiring the fish to find his way 

 from A to B, B to C, and from C to D. The results of these 

 and still others show exactly the same general mental 

 process as does the one described - - a process which I have 

 discussed at length elsewhere. 



Whatever interest there is in the demonstration in the case 

 of the bony fishes of the same process which accounts for so 

 much of the behavior of the higher vertebrates may be left to 

 the neurologists. The value of the experiment, if any, to 

 most students will perhaps be the extreme simplicity of the 

 method, the ease of administering it, and its possibilities. 

 By using long aquaria, one can study the formation of very 

 complex series of acts and see to what extent any fish can 

 carry the formation of such series. By proper arrange- 

 ments the delicacy of discrimination of the fish in any re- 

 spect may be tested. The artificiality of the surroundings 

 may, of course, be avoided when desirable. 



