248 The Structure of the Cochlea and the Perception of Tone 
disappearance of the cells forming the organ of Corti and of the mem- 
brana tectoria takes place simultaneously is strong, presumptive evidence 
that the latter structures alone constitute the mechanism essential for the 
function of hearing. 
Since these preparations show conclusively that the stimulation of the 
hair cells of the organ of Corti in this part of the labyrinth cannot be 
accomplished through a vibrating membrana basilaris, it is not logical to 
assume that in other parts of the cochlea, where the membrana basilaris 
may appear capable of vibrating, the stimulation of the hair cells must be 
accomplished through this means. 
In giving up this conception of the Helmholtz theory that the basilar 
membrane is a vibrating mechanism, the question arises: May not the 
several hair cells or groups of these cells when stimulated give the per- 
ception of particular tones, each acting as its own agent in selecting as its 
stimuli only such impulses as are produced by a particular tone? An 
objection to this hypothesis is the fact that anatomical study fails to 
discover those differences between the several cells which we might expect 
to find in case they possessed this varying function. A more serious 
objection, however, is the fact that this hypothesis fails to account for 
the peculiar secondary phenomena of tone perception which are explained 
so ingeniously by the resonator theory. ‘The fundamental principles in 
the resonator theory of Helmholtz still remain as the most plausible ex- 
planation of the various phenomena of tone perception. With the physio- 
logical and clinical facts which we possess, we can hardly escape accepting 
a resonator theory in some form. 
Moreover, if we assume that the several hair cells act in this way and 
yet accept the idea so plainly indicated by the structure of these cells, 
namely, that the transference of impulses to them is accomplished 
through the stimulation of their projecting hairs, then the question arises, 
can these hairs be stimulated directly by impulses in the endolymph 
without the intervention of the membrana tectoria? No fundamental 
objection to this theory is apparent, provided we can accept the anatom- 
ical relations usually given as existing between the membrana tectoria and 
the hair cells, namely, that this membrane floats in the endolymph free 
above these cells. The fact that this hypothesis fails to recognize any 
function for the membrana tectoria is, however, an objection to it. 
In an investigation into the character and relations of this most inter- 
esting membrane, I have been convinced that the tectorial membrane 
does not float free in the endolymph above the cells forming the organ of 
