The Senses and the Nervous System 1O3 



The fish has no outer ear. It has no middle ear. It does 

 have an inner ear, embedded in the bones of the skull. That 

 inner ear has the three semicircular canals, and the utriculus 

 and sacculus, but it has no spiral cochlea. The nearest thing 

 to it is a small projection of the sacculus called the lagena, 

 which has approximately the same location as the cochlea, 

 but none of its delicate machinery. 



Water is a much more positive conductor of sound-waves 

 than air. Therefore, the absence of an outer ear and a middle 

 ear would not in themselves preclude the possibility of the 

 fish hearing, for the sound-waves might impinge directly on 

 the skull with enough power to be sensed. Our ear-drum and 

 its ossicles are only mechanisms to transmute the sound- 

 waves in air into sound-waves in the liquid of the inner ear, 

 and the fish does not need them because its ear is already in 

 a liquid, the water. 



But the absence of the spiral cochlea is another matter. It 

 is this which furnished ammunition for those who did not 

 believe that fish hear. The cochlea, they pointed out, is in us 

 the ultimate instrument for hearing. The fish has no cochlea, 

 therefore it does not hear. Because two things are not alike, 

 they cannot produce the same result. This is doubtful logic, 

 and experimental results fail to support it. 



Complete proof of hearing came from a series of experi- 

 ments on goldfish in which great care was taken to meet the 

 objections which had been raised against previous demon- 

 strations. For instance, it had been argued that such noises 

 as are made by tapping on a tank, or by placing a tuning- 

 fork against the side of the tank, are not heard by the fish, 

 but sensed by him through the skin in the same way we feel 

 the sound when we place our hand on a piano. It is probably 

 true that some sounds, especially of a sharp or explosive 

 nature, do reach the fish in this way. To circumvent this 

 possibility, the experimenter took a small balloon, placed a 



