162 Irving Hardest}' 



different planes, as made by Coyne and Cannieu, '85, and here (Fig. 9), 

 indicate clearly its fibrous nature. 



It is not the intention of the paper to elaborate another theory of 

 hearing and to enter into a necessarily prolonged application and 

 defense of it. Leave is asked to merely suggest a modification of a 

 theory already advanced, namely an application to the tectorial membrane 

 of the telephone theory, heretofore applied exclusively to the basilar 

 membrane. Some of the considerations upon which this suggestion is 

 based are the following : 



(1) The prevailing acceptation is that the cochlea is the peripheral 

 organ of the auditory apparatus, and that the construction of this organ 

 is such as to be especially capable of serving, in conjunction with the 

 central nervous system, in the analysis of sound. 



(2) From their anatomical relationship, it is conceded that auditory 

 impulses are aroused in the acoustic nerve through the mediation of the 

 hair cells of the organ of Corti about which they terminate. 



(3) It is usually conceded and here accepted that the hair cells are 

 stimulated through the agitation of their hairs, but that the hairs are 

 neither suitably constructed, long enough, nor vary sufficiently in length 

 to be themselves acted upon selectively by the sound waves as transferred 

 to the endolymph. 



(4) All the recent conceptions of the process of hearing accept the 

 idea that the hairs of the hair cells are agitated by contact with the 

 under surface of the tectorial membrane, either by brushing against it 

 or by perpendicular impingement, produced either by vibrations of the 

 basilar membrane below or movements of the tectorial membrane above. 



(5) The numerous physiological and anatomical objections to it are 

 considered sufficient to render untenable the idea that the basilar mem- 

 brane is the vibrating mechanism either of the kind demanded by the 

 resonance theory or in accord with the telephone theory. 



(6) While experimental investigation has not yet been able to ascer- 

 tain the exact form of the wave motion in the endolymph of the cochlea, 

 it has been determined by observation of the action of the tympanic 

 membrane and auditory ossicles that the force of the motion produced 

 in the tympanic membrane by the atmospheric sound waves may He 

 increased thirty times in the transformation and transference of the 

 motion to the basis of the stapes and the membrane of the fenestra 

 vestibuli, and that the amplitude of the atmospheric waves may be 

 reduced as much as seventy-six times (or more). In this transference 



