452 C. W. PRENTISS 



the old theory which regarded the basilar membrane as a reso- 

 nator are many : 



1. The structure of the basilar membrane, clothed as it is by 

 several layers of cells, precludes its responding to delicate stimuli 

 (VonEbner'02). 



2. In the basal coil it is thick and rigid or may be replaced by a 

 plate of bone though in this region the spiral organ is normally 

 developed (Shambaugh '07). 



3. Hardesty has shown that the basilar membrane is merely a 

 flattened tendon, the fiber bundles of which are closely bound 

 together and thus could not vibrate separately. 



4. The pillars are also rigidly united, and it is probable that 

 the functions of the basilar membrane and of the pillars in con- 

 junction with the lamina reticularis is to give rigiditj^ to the 

 auditory cells in order that their hairs may respond more readily 

 to sound vibrations. 



5. The inner pillars do not always rest upon the basilar mem- 

 brane but upon the edge of the labium tjnnpanicum (Sham- 

 baugh, Hardesty). 



6. Sound waves entering the perilymph would affect the basilar 

 membrane more strongly from the side of the scala tympani yet 

 to do this would have to pass up and down the entire length of 

 the spiral. The amplitude of the vibrations would be lessened 

 by this and th^re' would be interference between the weaves going 

 up in the scala vestibuli and the waves descending in the scala 

 tympani. 



The objections raised against the basilar membrane do not 

 apply to membrana, and there are many points in its favor: 



1. The membrana is an exceeding delicate, chambered cuti- 

 cular membrane, flexible yet elastic and of a specific gravity only 

 slightly greater than that of the endolymph. 



2. It is co-extensive with the spiral organ while the basilar 

 membrane is not. 



3. It lies on that side of the spiral organ at which sound waves 

 would first enter the cochlea b}^ way of the scala vestibuli. 



4. It is attached along its inner edge to the labium vestibulare, 

 stretches over the spiral sulcus and overlies the spiral organ in 

 contact with and probably attached to its cells. 



