82 



PARKER— A CRITICAL SURVEY OF 



telephone which then yielded a tone of corresponding pitch. These 

 tones were of a musical quality and were accompanied by harmonics. 

 Thus the fishes in the aquarium could be subjected to any one of 

 the seven tones from 43 to 2,752 vibrations per second without the 

 least mechanical jar or disturbance. To be perfectly sure that the 

 operation of the telephone had no effect upon the fishes, except 

 through the sound it produced, its vibrating plate was removed, after 

 which it was operated in the aquarium as in the ordinary tests. 

 Under these circumstances no responses of any kind were obtained 

 from the fishes. The electromagnetic field and such other incidental 

 disturbances necessarily introduced by the telephone were thus 

 shown to be ineffective as stimuli. 



The reactions of Amiurus to the tones from the telephone are 

 given in the following table : 



TABLE I. 



Responses of Amiurus to Tones at Octave Intervals from 43 to 2,752 

 Complete Vibrations per Second. 



Each number represents the number of responses in ten trials, five on 

 each of two fishes. 



From the observations recorded in this table Parker and Van 

 Heusen (191 7, p. 477) concluded that Amhiriis is more generally 

 stimulated by tones of low pitch than by those higher in the scale, 

 that both the ears and the skin are effective as receptors for these 

 tones, but that the ears have a wider range than the skin. These 

 results completely confirm Haempel's conclusion that Amiurus can 

 hear. 



The judgments that from time to time have been passed in these 

 two lines of evidence have been almost as diverse as the evidence 



