240 PHYSIOLOGY CHAP. 



anatomy shows that in ascending the animal scale the cochlea 

 becomes increasingly complex in all its parts, until in man it 

 undoubtedly possesses a greater power of analysing tones than in 

 any other animal. 



To meet this objection A. D. Waller (1891) proposed an 

 ingenious modification of Eutherford's theory by assuming the 

 basilar membrane (or rather the entire organ of Corti) to represent 

 a long, narrow membrane which takes up the complex vibrations 

 of the membrana tympani and vibrates in its entire area to 

 all sounds, although more or less in some parts than in others, 

 according to the qualitative differences of the sonorous impulses 

 that impinge on it. If we picture the function of the organ of 

 Corti according to this interpretation, it seems, says Waller, to 

 give " what we may designate as acoustic pressure-patterns between 

 the membrana tectoria and the subjacent field of hair-cells. In 

 place of an analysis by consonation of particular radial fibres it 

 may be imagined that varying combinations of sound give varying 

 pressure -patterns comparable to the varying retinal images of 

 external objects." x 



While on Eutherford's theory analysis of tones takes place 

 not in the cochlea but in the brain, Waller holds that there must 

 be a certain degree of peripheral analysis, by means of the different 

 pressure-patterns produced by different tones and noises, although 

 he still leaves their more complete and delicate analysis to the 

 brain. 



Another opponent of Helmholtz' theory was M. Meyer (1898), 

 who also maintains that sound-analysis takes place in the organ 

 of Corti by vibrations, not of single radial fibres, but of more or 

 less extensive segments of the basilar membrane. The strength 

 of the tone sensations would depend on the length of the vibrating 

 segments, the pitch upon the frequency of vibration. 



Ter-Kuile (1900) supported a similar view. He started from 

 the fact that the base of the stapes at each incursion drives a 

 certain amount of lymph along the scala vestibuli, and thus 

 produces curvature of a portion of the basilar membrane pro- 

 portional in length to the period of the vibration, i.e. the depth 

 of the tone. So that the length of basilar membrane incurved 

 would form the measure of pitch. Each harmonic that accompanies 

 the deepest tones would cause a change in the modality of the 

 total excitation of the nervous apparatus, to which is due the 

 central perception of timbre. Ter-Kuile's theory does not 

 sufficiently account for the perfect analysis of compound sonorous 

 vibrations into the separate components in the cochlea. 



These incomplete and rudimentary theories of hearing put 

 forward by Waller, Meyer, and ter-Kuile are interesting as pre- 

 cursors of the new theory proposed by E. Ewald (1899-1903). 



1 Human Physiology, Waller, 3rd ed. p. 474. 



