778 THE SENSE OF HEARING 



cotrema to deep notes. In accordance with this view, it must be as- 

 sumed that each fiber has its own periodicity of vibration and is capable 

 of analyzing the simple waves of a particular compound wave. The 

 simultaneous vibration of a number of these fibers would of course 

 give rise to several sensations which are then fused in consciousness. 

 No definite statements can be made at the present time regarding 

 the manner in which the vibrations of these fibers are transferred to 

 the hair cells and endings of the auditory nerve. ^ 



Those physiologists who claim that these fibers are not sufficiently 

 long to serve as eflicient resonators, hold with Max Meyer^ that (a) the 

 analyzer is the basilar membrane itself, or (b) the vibrations in peri- 

 lymph are directly transferred to the hair cells through the inter- 

 vention of the endolymph of the central scala. The first view meets 

 with the same objections as the resonance theory of Helmholtz. The 

 second, on the other hand, has several points in its favor, because it 

 ascribes a perfectly definite function to the peculiar hair-like prolonga- 

 tions of these cells. It is conceived that these processes float free in 

 the endolymph of the central canal and are, therefore, in the best pos- 

 sible position to receive the vibrations set up in this fluid in conse- 

 quence of the transferred oscillations of the lymph in the adjoining 

 scala vestibuli. These hairs, therefore, serve the purpose of a battery 

 of resonators, capable of resolving the compound vibrations into their 

 simple constituents. In this case, the tectorial membrane is assumed 

 to play merely the part of a dampener similar to the felt pad upon the 

 strings of a piano. 



In support of the second view Ayers^ asserts that the membrana 

 tectoria, as seen in ordinary preparations, is an artefact and is nothing 

 more than a matted mass of hairs which in reality form a waving plume 

 extending from the surfaces of the hair cells through the endolymph 

 to be inserted upon the crest of the ridge immediately beside the 

 internal border of the organ of Corti. These long extended processes 

 are activated by the vibrations in endolymph and transfer their im- 

 pulses directly to the cells and adjoining nerve endings. 



To make this list complete, it might be mentioned that some 

 physiologists believe that the resonating organ is the tectorial mem- 

 brane itself which, however, vibrates only in segments and solely along 

 its thin margin. 4 Its vibrations are communicated to the hair cells, 

 the processes of which are in this case regarded as short stubby bristles. 



Whichever theory we may feel inclined to accept, it must be evident 

 that the final analysis of the sound waves is accomplished in the audi- 

 tory realm of the cerebral cortex. Subsequent to their association 

 they are projected to the place in the medium from which they appear 



1 Baginsky, Virchow's Archiv, xciv, 1883, 65. 



2 Zeitschr. fiir Psyc. und Physiol, der Sinnesorgane, xvi, 1898; also see: Ewald, 

 Pfliiger's Archiv, Ixxvi, 1899, 147, Yoshii, ibid., 1909. 



3 Journal of Morphology, 1892. 



* Ebner, in KoUicker's Handb. der Gewebelehre, iii, 1902, 958. 



