224: SPECIAL SENSES. 



by some anatomists that the filaments of the auditory nerves 

 terminate in the cells above described ; but this point is not 

 definitively settled. 



Functions of Different Parts of tJie Internal Ear. 



The precise function of the different parts which are 

 found in the internal ear is obscure, notwithstanding the care- 

 ful researches that have been made into the anatomy and the 

 physiology of the labyrinth. There are several points, how- 

 ever, bearing upon the physiology of this part of the audi- 

 tory apparatus, concerning which there can be no doubt : 



First, it is certain that impressions of sound are received 

 by the terminal filaments of the auditory nerves, and by 

 these nerves are conveyed to the brain. 



Second, the functions of the parts composing the external 

 and the middle ear are simply accessory. The sonorous 

 waves are collected by the cochlea and are conveyed by the 

 external meatus to the middle ear ; the membrana tympani 

 vibrates under their influence ; and they are thus collected, 

 repeated, and transmitted to the internal ear, under the most 

 favorable conditions for producing a proper impression upon 

 the auditory nerves. 



In view of these facts, we must look to the functions of 

 semicircular canals and the cochlea, for an elucidation of the 

 problem of the mechanism of the final process of audition ; 

 and, in doing this, we come at once to the question of the 

 relative importance of different divisions of the internal ear. 



Functions of the Semicircular Canals. In a memoir 

 presented v to the French Academy of Sciences, in 1824, Flou- 

 rens detailed a number of experiments on pigeons and rab- 

 bits, in which he destroyed different portions of the internal 

 ear. In these experiments, the results of which were very 

 distinct, it was shown that destruction of the semicircular 

 canals had apparently no effect upon the sense of hearing, 

 while" destruction of the cochlea upon both sides produced 



