394 HAVE FISHES MEMORY. 



hungry and to snap at anything that came its way, even at a finger 

 held out to it. In other words, it learned to eat in response to an 

 optical stimulus. Even then, however, it did not seize an earthworm 

 crawling through the water. To produce the act of eating it was 

 necessary that the optical irritation should l)e unvarying, and should 

 proceed from the surface of the water. The obvious inference that 

 the worm already in the water might be edible was not made. How- 

 ever, to be conclusive, the experiment ought to be repeated and more 

 carefully studied, for it is possible that the vision of motella is defective 

 under water. In general, my investigation has led me to believe that 

 in using fish in aquariums for experimental work many problems pre- 

 sent themselves whose solution would not be excessively difficult if 

 the questions were put with precision and if the observer took good 

 care not to read more than they warrant into the results of his inquir3^ 

 In the above presentation psychologic problems in the narrow sense 

 of the term have been avoided. To make headway on this field of 

 inquiry we must for the present confine ourselves strictly to observa- 

 tion. A])ove all, Ave must take heed not to read into our observations 

 the probabilities that might be sanctioned by reasoning from analog}'. 

 Therefore no attempt was made to formulate an attitude with regard 

 to the question: Do fishes know an^^thing of the processes described? 

 Have they any sort of consciousness i At present such problems are 

 imp()ssil)le of solution. I found no observation making inevitable the 

 opinion that fishes not merel}' are open to impressions but are actually 

 aware of them, and tliat the}' were in a single instance influenced by 

 them to change their conduct in a wa}' possible onl}^ when an impres- 

 sion has been observed, has been meditated on, and is applied in a 

 subsequent emergency. All the phenomena were capable of a simpler 

 explanation. For a stimulus to evoke a secondary effect it must not 

 necessarily be observed, and its later application does, not absolutely 

 demand conscious memory. The science of to-day is not aware of 

 phenomena necessarily involving the recognition and use of stimuli as 

 such until the higher animals ar^ reached. It is probable that the seat 

 of this highest function is to be sought in the cortex of the brain. 

 Moreover, the cortex alone is plowed through with the paths of 

 association sufficing for the manifold coordinations that are wholly 

 lacking in fishes. 



