No. I.] THE VERTEBRATE EAR. 267 



at right angles to the plane of the membrane, every fibre of any 

 strip vibrating practically independently. He claims to show- 

 by this mathematical analysis that every excitement of a bundle 

 of transverse fibres by the respective fundamental tone must 

 be accompanied by weaker excitements of the unevenly num- 

 bered harmonic undertones, the intensity of which would be 



multiplied by the factors \, ^-^, and generally -^- This hypothe- 

 sis, advanced by Riemann in his Musikalischc Logik, is consid- 

 ered by Helmholtz to be tenable, though nothing of the kind 

 is observable in the ear. Helmholtz states that probably the 

 appendages of the basilar membrane greatly impede the forma- 

 tion of tones with nodes. 



Paul Meyer has given special attention to the structure of 

 the basilar membrane among the Sauropsida, and he finds that 

 among most reptiles it is composed not of a series of parallel 

 fibres, but of a homogeneous plate of substance, and he is sure 

 that in no case will it allow of the interpretation placed on this 

 structure in the Mammalia ; and he concludes after this study of 

 the basilar membrane in reptiles and birds and a consideration 

 of the facts and theories of other writers, Helmholtz especially, 

 that "une membrane fort peu elastique d'une epaisseur tres ap- 

 preciable superficiellement striee, composee de diverses couches, 

 dont, disons-le en passant, I'epaisseur relative varie avec I'age, 

 tel est, en derniere analyse, I'appareil aquel on voudrait rapporter 

 nos plus fine sensations auditives." "Ainsi done, pas plus que 

 I'organe de Corti que la membrane de recouvrement, la mem- 

 brane basilaire ne repond aux conditions necessaire pour servir 

 de base." 



Owsjannikow (p. ii) did not find (in his studies on Petromy- 

 zon) that the hair cells were nerve-end cells, but concluded that 

 the nerve fibres ended freely in the basement membrane under 

 the sensory epithelial cells. This concerns us here only in so 

 far as it influenced his physiological conceptions of the modus 

 of the transmission of the vibratory motion from the endolymph 

 to the nerve fibre. Owsjannikow believed that the sensory 

 cells {i.e. in Petromyzon) did not possess auditory hairs. 



"Ein solcher Zusammenhang [i.e. between nerve and hair 

 cell] ist kaum nothig. Nehmen wir an, dass durch irgend einen 

 Ton die Endolymphe in Bewegung gesetzt wird und die Wellen 



