ox THE XATUEE OF THE TECTORIAL MEMBEANE AND 



ITS PEOBABLE EOLE IN" THE ANATOMY 



OF HEAEING. 



BY 



IRVING HARDESTY. 



From the Anatomical Lahoratorp of the TJniversity of California. 

 With Twelve Figures. 



Tlds investigation has been undertaken with the hope of contributing 

 something to the knowledge of the shape, character and intimate struc- 

 ture of the mammalian tectorial membrane. Of all the organs of 

 special sense, the ear seems to be the most complex and its functional 

 action least understood. As voluminous as is the literature upon it, 

 investigators, as yet, by no means wholly agree even as to the detailed 

 anatomy of the inner division of the auditory apparatus. In rimning 

 over the papers published, one is struck by the fact that they may be 

 quite definitely separated into two classes: anatomical investigations, 

 and physico-physiological treatises, the latter being, in most cases. 

 ]nirely theoretical. Quite often does it appear that the investigator in 

 the latter class maintains that his conclusions are correct on the basis 

 of his correct application of physics and mathematics to structures of 

 unproven existence. 



Of the four mechanisms deemed essential in the auditorv apparatus, 

 all the recent papers practically agree as to the identity and action of 

 the transforming and regulation mechanism and the conducting mechan- 

 ism, and all agree that the hair cells of the organ of Corti comprise 

 the stimulative mechanism; but they disagree as to what comprises the 

 vibratory or resonance mechanism. Most of the older papers attribute 

 the faculty of selective or sympathetic vibration, in accord with the 

 waves imparted to the endolymph in the cochlea, to the basilar mem- 

 brane. Of the four more important papers of recent date, two still 

 assume that the basilar membrane is adapted for and serves as the 

 vibratory structure, while the other two advance the idea, but occa- 

 Americax Journal of Anatomy. — Vol. VIII, No. 2. 



