The Nature of the Tectorial Membrane 161 



labium vestibulare of the spiral limbus. In the apical turn, at least, its 

 outer edge cannot be attached to the lamina reticularis, for this edge in 

 the first half-turn (Fig. 6) may extend into the space of the ductus 

 cochlearis a distance of nearly half its width beyond the organ of Corti. 



Shambaugh, '07, urges the objections, accredited to him above, against 

 the possibility of the basilar membrane being a resonance mechanism, 

 and, from appearances in some of his sections, concludes (1) that the 

 tectorial membrane does not lie free in the endolymph over the organ 

 of Corti, but is attached along Hensen's stripe to the inner supporting 

 cells of the organ; (2) that "the hairs of the hair cells project normally 

 into the under surface of the tectorial membrane"; (3) that "the size 

 of the membrana tectoria near the apex of the cochlea is many hundred 

 times its size near the beginning of the basal coil"; and (4) he con- 

 cludes further that, in structure, the tectorial membrane consists of "au 

 immense number of delicate lamellae taking their origin from the 

 portion of the membrane which rests upon the labium vestibulare." 

 From these conclusions and the conclusions generally accepted as to the 

 relation of the tectorial membrane and the hair cells to stimulation of 

 the acoustic nerve terminations, he advances a theory that the tectorial 

 membrane consists of a series of resonators (the lamellae) which are 

 capable of responding to the most delicate impulses passing through the 

 endolymph, claiming that the great variation in size of the membrane 

 from one end to the other, suggests the possibility that, by acting the 

 part of a resonator, it is capable of responding in different parts to 

 impulses (tones) of different pitch. Shambaugh, in applying his 

 theory, claims with reason that all the observations by Helmholtz and 

 his followers supporting their resonance theory apply more readily to the 

 tectorial membrane as a resonator than to the basilar membrane, and 

 proceeds to explain the pathological phenomena of "tone islands" 

 "diplacousus hinauralis dysharmonica" and "tinnitus aurium" on the 

 basis of a resonating tectorial membrane. 



Some of the observations both made and cited in this paper are not in 

 accord with the premises from which Shambaugh's theory follows. In 

 the first place, it is considered probable that the tectorial membrane 

 does lie free over the organ of Corti and that the auditory hairs do not 

 project into it. In the second place, it is not a lamellated structure. 

 Ever since 1869, when Bottcher teased portions of it and found them to 

 contain fibers, the fibrous structure of the membrane has been conceded 

 by all who have studied it with reference to its structure. Sections in 



