382 HAVE FISHES MEMORY. 



most readily to chemical irritations see ordinarily. On account of 

 the conditions in the aquarium, he could come to no definite conclusion, 

 and he supposed that the darkness in the depths of the water mio-ht 

 bring- about different conduct. More than a hundred of my letters 

 report that fish in ponds and aquariums swim close up to the attendant 

 as soon as they catch sight of him, and in a number it is explicitl}^ 

 stated that the color of his clothing or an habitutil movement of his at 

 once attracts the shoal. 



Do fishes hear? Of late years it has been determined that two dif- 

 ferent sense organs lie c-lose to each other in that part of the body 

 usually designated as the auditory apparatus. The labyrinth, beyond 

 a doubt, regulates the action of the muscles for the orientation of the 

 body. The cochlea, on the other hand, seems to serve only for the 

 reception of sound sensation. The former apparatus, or an ai)paratus 

 of equal functional value, occurs alike in vertel)rates and in inverte- 

 brates, as, for instance, in crabs. The real organ of hearing, how- 

 ever, the cochlea, is not met with lower down than the amphi})ians; 

 fishes lack it entirel3^ It is, of course, possible that th(^ latter ma}' 

 be able to receive sound impressions through some part of the laby- 

 rinth. In fact, it would seem to be the case in view of the numerous 

 reports about fish sunuuonod to ])e fed by the ringing of a bell. 

 Despite his manj^ experiments in the aquarium, Bateson could never 

 satisfy himself that his fish actually heard. Onl}' very loud noises, 

 such as the firing of a shot or an explosion on the street, disquieted 

 them, A large number of my correspondents mention that fish, 

 especially of the carp-like forms, came to be fed at the sound of a 

 bell or whistle. One of them relates that trout were attracted by the 

 barking of a dog in the habit of accompanying the attendant. But, in 

 all these cases, the possiliility of an optical impression is not excluded 

 absolutely. Herr W. von Derschin, a breeder of wide experience, 

 writes me that in his judgment the bell plays no part at all. 



Kreidl's experiences, gathered at a pond where the fishes were sum- 

 moned by a bell, made him suspect that the}^ were attracted by the 

 appearance of the attendant or by the percussion caused by his steps. 

 He instituted a careful investigation, though it did not extend beyond 

 goldfish in an aquarium. Sound waves originating in bells and whistles 

 were conducted through the air to the fish, or reached the fish through 

 the water by means of suspended springs operated by electricity. The 

 fish were observed from a distance with the aid of a mirror. He did 

 not notice anything to indicate that the sounds had been heard by the 

 fish. He thea made them more sensitive to impressions of all sorts by 

 poisoning ^em to a slight degree with strychnine. Even then their 

 movements betrayed no consciousness of the sounds. On the other 

 hand, they were made restless by a clapping of the hands, the report of 

 a revolver, or a stamping of the foot. The same restlessness was pro- 



