582 SCIENCE PROGRESS 



living their ordinary natural life. The essential points of his 

 experiments were (i) the use of fish in their natural environ- 

 ments ; (2) the use of a powerful source for the sound (a bell 

 some 17 cm. in diameter); (3) great care in shielding the water in 

 which the fish were swimming from heavy mechanical vibrations 

 set up by the bell ; (4) the location of the source of sound in the 

 water. 



The results of his experiments showed that the fish were 

 sensitive to the sound of the bell within a radius of some 8 to 10 

 yards. 



Anyhow, after Parker had succeeded in satisfying himself 

 that the ear was sensitive to vibration, in 1908 he proceeded to 

 try to locate the actual receptive organ. 1 Taking the Squeteague, 

 a fish in which the sacculus is of very great size, he attempted 

 to put the great saccular sense-organ out of action by pinning 

 the otolith away from the sensory epithelium. Under these 

 conditions nearly all response to vibration was lost. Parker 

 therefore concluded that the otolith organs were the seat of a 

 vibration sense. 



Further confirmation that the otolith organs respond to 

 sound is furnished by an important experiment by Piper. 2 

 When the otoliths are exposed in the severed head of a Pike 

 and brought within range of the sound of a pipe, electrical 

 changes occur in the otic nerve such as are normally associated 

 with the passage of a nervous stimulus. 



In addition to the above direct experimental evidence of a 

 generalised and dull auditory power in fishes, there is evidence 

 of an indirect circumstantial character that also points to the 

 same conclusion. 



In the first place, many fishes, 3 particularly among the 

 Sciaenidae, Siluridse and Triglidae, make sounds which are quite 

 distinctive and sometimes remarkably loud. Possibly, in some 

 cases, these sounds are the by-products of some other 

 activity ; they may also be accompanied by mechanical vibra- 

 tions that can be felt. Whether the fish are also sensitive to the 

 true sound vibrations, it is almost impossible to say; the fact 

 that they make them, often as a secondary sexual action, favours 

 the assumption that they are also sensitive to them. 



1 Parker, Bull. Bureau Fisheries U.S.A. 28, 1908. 



2 Piper, Munch. ?ned. Wochenschr. 53, 1906, p. 1785. 



3 Tower, Annals N.Y. Acad, Sci, xviii. 1908, p. 149. 



