vin FUNCTION OF COCHLEA 387 



vibrations of one quality only ; the other, central, in the 

 brain, capable of producing a psychical effect d one 

 quality only. It does not follow, however, that we are 

 distinctly and separately conscious of the nervous disturb- 

 ance in each central end-organ, it does not follow that 

 we have as many distinct and separate kinds of conscious 

 sensation as there are peripheral and central end-organs, 

 though how many such distinct kinds of sensation we 

 may have we do not know. Just as the peripheral 

 mechanism sifts out the several vibrations of which a 

 musical sound is composed, and transmits them separ- 

 ately, so, by a reverse operation, the central mechanism 

 probably pieces together the nervous disturbances of a 

 number of central end-oi'gans, and thus produces a 

 sensation whose characters are determined by a com- 

 bination of the nervous disturbances taking place in each 

 end-organ. 



Some such a view is indeed exceedingly probable ; but 

 it must be remembered that we do not at present at all 

 understand the exact mechanism by which each particular 

 vibration excites its corresponding nerve filament. The 

 nerve filaments appear to end in the epithelial cells bear- 

 ing short hairs, which lie on each side of the rods of Corti ; 

 and we may therefore conclude that these "hair-cells" 

 have some share in producing the effect. But the whole 

 matter is at present very obscure ; the functions of the 

 rods of Corti are particularly difficult to understand ; for 

 these do not seem in any way connected with the nerve 

 filaments, and their movements can only affect the latter 

 by influencing in some way the hair-cells. 



The fibres of the cochlear nerve, or their endings in the 

 brain itself, may be excited by internal causes, such as 

 the varying pressure of the blood and the like ; and in 

 some persons such internal influences do give rise to 

 veritable musical spectra, sometimes of a very intense 

 character. But, for the appreciation of music produced 

 external to us, we depend upon the organ of Corti being 



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