148 American Fisheries Society 



how Kreidl had fallen into error. Bigelow repeated 

 Kreidl's experiments. He found, however, that when he 

 pulled out the internal ear through an opening in the 

 top of the head, he did not get it all. The part of the 

 internal ear concerned in hearing remained in the head 

 and the fish could still hear. The part removed in this 

 operation is not concerned in hearing, but is an organ 

 of equilibrium by which the fish keeps its balance. Its 

 removal does not affect hearing. When Bigelow cut the 

 nerve to the internal ear the goldfish were rendered quite 

 deaf. Thus at last it was shown not only that fish hear 

 but hear with the ears. As in other animals the internal 

 ears are at the same time organs of equilibrium. 



Haempel (1911), has more recently reinvestigated the 

 question, and has used for the purpose European min- 

 nows and trout and an American fish, the common bull- 

 head (Ameiurus nebulosus). He arranged an electric 

 bell suspended in an air-filled metal tube which was im- 

 mersed in the water of the aquarium. He also employed 

 a loud whistling sound made by blowing through the 

 fingers. Both sounds were thus produced in air from 

 which they penetrated into the water of the aquarium, 

 but presumably with greatly reduced intensity. Normal 

 young bullheads responded to both sounds. A young 

 bullhead from which the internal ear had been removed 

 gave no response to either sound. Haempel concludes 

 that the young bullhead hears sounds produced in air. 

 On the other hand he was unable to get evidence that the 

 minnows and trout with which he worked are able to 

 hear. He considers them quite deaf. It is possible that 

 the fish that Haempel found unable to hear sounds pro- 

 duced in air would respond to those produced directly in 

 water. In that case his results would agree with those 

 of Parker and Bigelow. A difference in the sensitive- 

 ness of fish of different kinds to sound is to be expected. 

 The bullhead may be so sensitive that when in water it 

 is able, as Haempel's evidence indicates, to hear sounds 

 made in air. Other fish such as the minnows and trout 

 used by Haempel may be able to hear only the more in- 



