No. I.] THE VERTEBRATE EAR. 2/1 



The third demand of physiological acoustics is satisfied by 

 the membrane of Corti, which acts as a damping apparatus. 

 Its constitution and position and all its peculiarities speak for 

 this view of its function. It is a most delicate damping appara- 

 tus. By each change in the endolymph the damper is pressed 

 down upon the ends of the hair cells, and in this manner regu- 

 lates above everything else the rustling noises, which might 

 impair the purity of the musical tones. 



We hear with the vestibule ; we understand with the cochlea. 

 The cochlea is, then, not so much an organ for simple audition, 

 but more for the complicated processes of the differentiation 

 and perception of musical tones. 



The part played by the central nervous system in audition is 

 not considered by Lavdowsky, since it lies beyond the scope of 

 his paper. 



Meyer is thoroughly convinced that the hair-bearing cells, and 

 they alone, subserve the auditory function by being sensitive to 

 vibrations and transmitting them to the central nervous system, 

 as he explains in the following words, already referred to in the 

 account of Lavdowsky's views : — 



*' Ces cils (les crins des ampoules et les pinceaux du saccule) 

 relativement assez epais, raides, vitreux, cassants, semblables 

 en quelque sorte a des verges de verre ou d'acier, formant par 

 leur insertion a peu pres lineaire des faisceux minces, eux- 

 memes fixes sur une sorte de plateau du meme nature, indepen- 

 dant du protoplasma de la cellule qui les porte, ces cils ne 

 doivent-ils pas presenter au plus haut degre la propriete de 

 vibrer pour leur compte, de vibrer par influence pour un ton 

 determine t ne constituent-ils pas, en un mot, un appareil de 

 resonance presque mathematique, une sorte de diapaison, infini- 

 ment superieur dans tons les cas a ces cordes basilaires aux- 

 quelles la theorie de Hensen voulait faire jouer le meme role t 

 a. une theorie solide de la perception des sons, et deja, par ex- 

 clusion nous arrivons a chercher la clef du probleme dans le 

 seul element du limagon que nous n'ayons pas encore soumis 

 a une etude physiologique rigoureuse, dans les cellules auditives 

 elles-raemes." 



Hensen, while agreeing in general with Helmholtz's account 

 of the auditory physiological processes, gave the following de- 

 scription of the manner in which he conceived the parts of the 



