206 SPECIAL SENSES. 



any distinct portion of the auditory apparatus, like the mem- 

 brana tympani. This, like all other parts of the apparatus, 

 except the auditory nerves themselves, has simply an acces- 

 sory function. If the regular waves of a musical tone be 

 conveyed to the terminal filaments of the auditory nerves, 

 these waves make their impression and the tone is appre- 

 ciated. It makes no difference, except as regards intensity, 

 how these waves are conducted ; the tone is appreciated by 

 the impression made upon the nerves, and the nerves only. 

 The waves of sound are not like the waves of light, re- 

 fracted, decomposed, perhaps, and necessarily brought to a 

 focus as they impinge upon the retina ; as far as the action of 

 the accessory parts of the ear are concerned, the waves of 

 sound are unaltered ; that is, the rate of their succession re- 

 mains absolutely the same, though they be reflected by the 

 concavities of the concha, and repeated by the tympanic 

 membrane. Even if we assume that the membrane, under 

 normal conditions, repeats musical sounds by vibrations pro- 

 duced by influence, and that this membrane is tuned by vol- 

 untary muscular action so that tones are exactly repeated, the 

 position of these tones in the musical scale is not and cannot 

 be altered by the action of any of the accessory organs of 

 hearing. The fact that a person may retain his musical ear 

 with both membranes destroyed is not really an argument 

 against the view that the membrane repeats tones by influ- 

 ence ; for, if musical tones or noisy vibrations be conducted 

 to the auditory nerves, the impression produced must of ne- 

 cessity be dependent exclusively upon the character, regu- 

 larity, and number of the sonorous vibrations. And, again, 

 the physical laws of sound, which are fixed and unchange- 

 able, teach us that a membrane, like the membrana tympani, 

 must return or reproduce sounds which are in unison or are 

 harmonious with its fundamental tone, much more perfectly 

 than discordant or irregular vibrations. In a loud confusion 

 of noisy sounds, we can readily distinguish pure melody or 

 harmony, even when the vibrations of the latter are compara- 



