Sense of Heaeing. 105 



the skin, ia a nerve; that all these nerves, from the base of every 

 scale, lead to a large ganglion situated on the center of the fore- 

 head of the fish below the eyes; and that nerves from this gang- 

 lion communicate to the internal ear. These nerves, at the base 

 of each scale, are formed to receive vibrations in water. Any 

 vibration in water reaching the scales of the fish is thus communi- 

 cated to the internal ear. If, as was the fact, one of the timbers 

 that supported the flume rested in the running water on the 

 ground, the vibrations of this running water on the ground 

 would be carried by this timber to the flume and to the water in 

 it, four feet above, and the ear of the fish would separate and take 

 cognizance of the difference in the vibrations, as the human ear 

 in the air distinguishes the difference between the voices of 

 friends." 



As many fishes utter sounds, some so loud as to be heard 

 in the air, it is reasonable to suppose that such sounds are 

 heard by other fishes. Most fishes are capable of receiving 

 impressions, through three sets of sense organs' viz., the 

 ears, the skin, and the lateral line organs. Mr. H. G. 

 Parker, after many experiments, has determined that " the 

 skin is affected by surface waves and by currents; the 

 lateral line organs by slight inaudible movements of the 

 whole mass of water ; and the ears by the still more delicate 

 vibrations of water particles, sound." 



Among the most intelligent investigations in this direc- 

 tion in recent years have been the experiments just men- 

 tioned, of Mr. H. G. Parker, Assistant Professor of 

 Zoology, Harvard University, under the auspices of the 

 TJ. S. Bureau of Fisheries, at its laboratory at Woods Hole, 

 Mass., during the past year or two. He made many experi- 

 ments dealing with the cutaneous nerves, the lateral organs 

 and the auditory nerves, on such fishes as were most readily 

 procured, principally with killifishes {Fundulus hetero- 

 clitus). These experiments were not confined to fishes in 



