THE SENSE OF HEARING IN FISHES. 73 



by the fact that the ear of this fish was unprovided with a cochlea, 

 that organ which is present in the ears of the higher vertebrates and 

 is especially concerned with hearing. 



Some seventeen years later and apparently without knowledge of 

 de Cyon's results, Kreidl (1895) undertook the study of the func- 

 tion of the fish ear. His work was carried out on the goldfish 

 (Carassius aiiratus) and with much care and many precautions. 

 Normal fishes in a carefully guarded aquarium were found not to 

 respond to sounds produced in the air, or even in the water itself, 

 though the creatures did react to a blow on the cover of the aqua- 

 rium. Fishes poisoned slightly with strychnine were more sensitive 

 and, though they did not respond to a bell or whistle sounded in the 

 air nor to a metallic rod made to vibrate in the water, they did 

 respond to the tapping of the rod, to the clapping of hands, and to 

 the report of a pistol. After the removal of the ears, the equilibrium 

 of these fishes was greatly disturbed, as was to be expected from 

 the previous work of Loeb {i^gia, 1891&), Lee (1892, 1893, 1894) 

 Kreidl (1892), and Bethe (1894, 1899), t»ut the animals showed no 

 change in their responses to sounds*. Kreidl (1895, p. 464), there- 

 fore, concluded that it could not be shown that the goldfish hears 

 and that the responses that this fish exhibits to sound-waves were 

 dependent upon a specially developed skin-sense. 



The year following, Kreidl (1896) carried out some simple but 

 conclusive experiments at Krems where large numbers of trout and 

 other fish were bred for market purposes and where the fish were 

 said to come for food at the sound of a bell. Kreidl showed that 

 when the bell was rung by an unseen person, the fishes failed to 

 assemble and that the real stimuli that caused them to come to- 

 gether was the sight of the keeper and the vibration of his tread. 

 Thus Kreidl was confirmed in his view that fishes, including both 

 goldfishes and trout, do not hear. 



Kreidl's papers were soon followed by one from Lee (1898), who 

 tested a number of species of fishes by subjecting them to the sounds 

 of the human voice, the clapping of hands, and the striking of stones 

 both above and under water. Though the fishes tested proved to 

 be very sensitive to the jarring of the tank in which they were and 

 to concussions on its walls, they did not respond to sounds produced 



