THE VOICE OF ANIMALS 



HROUGHOUT the depths 

 of the sea, silence, as 

 well as absolute darkness, prevails. 

 The sun penetrates only a short dis- 

 tance below the surface, at most a few 

 hundred feet, and all disturbance from storms ceases far 

 above that depth. Where the pressure is a ton or more 

 to the square inch, it is very evident that no sound vibra- 

 tion can exist. Near the surface it is otherwise. The 

 majority of fishes have no lungs and of course no vocal 

 chords, but certain species, such as the drum-fish, are able 

 to distend special sacs with gas or air, or in other ways 

 to produce sounds. One variety succeeds in producing a 



