INTELLIGENCE AND SPECIAL SENSES. 61 



the skin, the limbs, or any other part of a fish differs from that of 

 a quadruped or from our own. 



"The microphone has gone far toward proving what philoso- 

 phers had previously become convinced of by deductive reason- 

 ing, that there is no motion without sound, and therefore that 

 sound is present in numberless instances not evident to our senses. 

 For our perception of sound we are dependent upon our sense of 

 hearing, which is adapted only to a certain range of sounds ; and 

 this range differs in human individuals, for we all know that some 

 other persons hear sounds imperceptible to us. Still more is this 

 true of other animals ; they may hear what we can not, yet be 

 deaf to sounds audible to us. 



" Strict experiments upon the hearing of fishes have yet to be 

 made. Most of the observations yet made are faulty, either be- 

 cause, first, the observer has supposed that the fish ought, if it 

 can hear, to notice a sound he makes for the purpose ; or, sec- 

 ond, he has argued, from the standpoint of his own senses, that 

 if a fish hears, the range of its hearing must be nearly the same 

 as his own. 



" To conclude: that fish have ears, is indisputable ; that they 

 hear some sounds produced in the water, scarcely admits of ques- 

 tion ; that they hear some sounds produced in the air, even 

 though they may not take notice of them, is probable, but lacks 

 (so far as I know) experimental proof ; that they do not hear 

 many sounds which we hear, or at least do not discriminate be- 

 tween sounds which we, with our more highly organized organs, 

 readily distinguish, is almost certain. A.11 of which ends in this, 

 that fishes hear, but their senses differ in range and delicacy from 



