294 POWER OF HEARING OF FISH. 



convey the watch to a greater distance from the 

 ear and press it against the teeth, or if we rest 

 one end of a rod of wood against the watch and 

 the other against our head, we hear the ticking 

 with remarkable distinctness. In the language 

 of science, solid and dense bodies vibrate with 

 greater intensity than lighter media, such as the 

 atmosphere. When the watch is held nigh to the 

 ear the atmosphere is the conductor; when the 

 watch is connected with the ear, by the interven- 

 tion of a rod of wood, or the solid parts of the 

 head, these are the conductors. Now the appa- 

 ratus of hearing of the fish presents conditions of 

 the latter kind; water, a denser body than air, is 

 the conducting medium ; and the solid mass of the 

 head, and, in fact, of the entire body, completes 

 the conduction to the vital apparatus. Hence in 

 fishes, a humble contrivance is capable of effect- 

 ing the same end as the high-toned instrument of 

 terrestrial animals. Fishes must, therefore, hear 

 with moderate acuteness, particularly such sounds 

 as occasion a vibration of the element in which 

 they reside, for example, an approaching footstep ; 

 while the sounds which proceed from musical 

 instruments, being less easily conveyed, are pro- 

 bably unknown to them ; certainly this is the case 

 with regard to tone. Those curious porcelain- 

 like bodies, which are found in the head of the 

 fish, and which must be known to every investi- 



