256 The Structure of the Cochlea and the Perception of Tone 
cousis binauralis dysharmonica,’ and of “tinnitus aurium” are all 
plausibly accounted for in this conception of the physiology of tone 
perception. 
11. To restate briefly the process by which the phenomenon of tone 
perception is accomplished: The sound waves conducted from the air 
impinge upon the membrana tympani, producing vibrations in it. ‘These 
vibrations conducted along the chain of ossicles transmit impulses to the 
intralabyrinthine fluid through the medium of the foot-plate of the stapes. 
The impulses originating in the fluid in the vestibule pass directly into 
the scala vestibuli and through the membrane of Reissner to the endo- 
lymph where sympathetic vibrations are imparted to the several parts 
of the membrana tectoria depending on the pitch of the tone. The vibra- 
tions of the membrana tectoria in turn stimulate the hairs of the hair 
cells which normally project into its under surface. The nerve impulses 
originating from all the hair cells thus stimulated by a particular tone 
come together in the brain center in the cortex when the tone picture 
forms the final step in the process of tone perception. 
** * * 
Since placing this paper in the hands of the publishers my attention 
has been called to an article by K. Kishi, which appeared in a recent 
number of Pfliiger’s Archives (Band CXVI, 8. 112). Kishi expresses 
the view that the basilar membrane is not a vibrating structure. He 
has failed, as have others, apparently, to find what appears to me as a 
fundamental objection to this hypothesis, in that as the lower end of the 
basal coil is approached this structure not only becomes so stiff and 
rigid as to preclude the possibility of its being capable of vibrating but 
even its complete absence is sometimes noted. Kishi concurs in the view 
previously expressed by others, Siebenmann, for example, that the mem- 
brana tectoria appears to be the logical structure for applying stimulation 
to the hair cells. Just how the tectorial membrane accomplishes this 
function Kishi does not elucidate. His views regarding the character 
and relations of the membrana tectoria are quite at variance with my 
own findings, as shown in this article. He believes that this membrane 
is a taut structure attached to the labium vestibulare and to the outer 
end of the reticular membrane. The illustrations which Kishi pub- 
lishes of a flattened-out tectorial membrane lying over the organ of 
Corti is not unlike others that appear in the literature and represent quite 
common findings, of which I have a great many. That such a membrane 
