No. 435.] SENSE OF HEARING IN FISHES. 



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waters about the United States Fish Commission Station at 

 Woods Hole, Massachusetts, where my work was done I his 

 fish proved very hardy and in every way satisfac tory for the 

 work. 



Three classes of killifishes were tested ; first, those that were 

 entirely normal ; secondly, those in winch the nerves to the ears 

 had been cut ; and, thirdly, those whose outer surfaces had been 

 rendered insensitive by cutting the nerves to the skin. The fishes 

 were easily etherized and cutting the nerves to the ears proved to 

 be a simple though delicate operation. To render the skin insen- 

 sitive, it was necessary to cut the fifth and seventh nerves, the 

 lateral line nerves and the spinal cord, but from this apparently 

 severe operation the fishes almost invariably recovered, fed well, 

 and continued normally active for several weeks. 



When a normal fish was placed in the cage and the bass viol 

 string set in vibration, any one of four responses might be 

 observed: first, the rate of the gill movements increased for a 



motion, or, if in motion, their rate was increased; thirdly, the 

 tail fin often vibrated ; and, finally, the whole fish might give a 

 spring as if startled by the sound. Of these four reactions, tin- 

 one most satisfactory for observation was the movement of the 



ten tests with the sounding apparatus responded with the pec- 

 toral fins ninety-six times in the total hundred. This number 

 may be taken as a basis of comparison for the fishes upon which 

 operations had been performed. 



respect between normal and earless goldfishes. Although at 



