FISHES AND FISHING. 85 



lection, vary extremely in their shape, and the dispo- 

 sition of their grooved surfaces, in which they receive 

 the auditory nerves. But in none of these ossicula 

 can be found a trace of phosphate of lime, or of car- 

 bonate of magnesia, they being composed of animal 

 matter somewhat about one-fourth, and carbonate of 

 lime three-fourths. The gelatinous fluids mentioned, 

 are, no doubt, renewed from the mucous^^membranes 

 lining the several cavities, as in man. 



It will now be necessary to give a short account of 

 the organ of hearing in man, whereby the comparative 

 anatomical structure and physiological functions can be 

 properly estimated. In the human race, the undula- 

 tions of air occasioned through it being set in motion by 

 substances being struck against each other, — ringing of 

 bells, explosion of fire-arms, music, the human vdice, 

 or other disturbances of the air, causing it to be set in 

 motion, these undulatory waves enter the auditory 

 passage, and occasion the membrana tympani (vulgo, 

 the drum of the ear) to vibrate ; the ossicula, or chain of 

 bones within this membrane, one of which is attached 

 to the middle of this membrana tympani, on its 

 inside, are consequently set in motion, and that 

 motion is communicated to the delicate fibres of the 

 Boft or sensitive portion of the auditory nerve, which 

 floats in a fluid, which motion is continued and con- 

 veyed to the base or seat of the auditory nerves in the 



