150 Irving Hardesty 



manipulation may result either in its being drawn in contact with the 

 organ below or in its being lifted well away from the organ. Sections 

 often show it even pressed upon the organ, but the majority of sections 

 show it directed in various angles, entirely free from the organ, and 

 many of the older pictures of it are thus drawn. When caught more 

 nearly in its normal position with its under surface parallel with and 

 near the surface of the organ of Corti, delicate filamentous connections 

 are often apparent, but such connections can be justly explained as 

 brought about by crumplings or abrasions of the fibers in the under 

 surface, or by bits of the very thin accessory membrane coming in con- 

 tact with the auditory hairs or other elements, the appearance of con- 

 tinuity being accentuated by adhering coagulum filaments precipitated 

 from the albumins and globulins of the endolymph. 



(3) From the process of its development, it seem probable, contrary 

 to Eickenbacher, but in accord with Von Ebner, that, a priori, the 

 membrane is free from the underlying epithelial structures. During its 

 development it is attached only to the epithelial cells giving origin to it, 

 and since its outer zone acquires its adult position over the organ of Corti 

 only by the recession of the parent epithelium and the consequent dis- 

 placement of the organ, one must at least assume that, if attachment 

 to the organ exists, it must be developed after the development of both 

 the organ and the membrane. This is hardly probable and, moreover, 

 it is hardly necessary to an explanation of the role of the organ in the 

 phenomena of hearing. 



On the Anatomy of Hearing. 



It may be said that the tectorial membrane is comparable and 

 analogous to the otolithic membranes of the cristas and maculae acus- 

 ticae, except that it is neither developed by nor upon cells belonging in 

 the group of special sensory cells with whose stimulation it is concerned, 

 and except, further, that in the higher animals it is not beset with 

 calcareous products. 



Lavdowsky, '77, and others, including Ayers, '91, have called atten- 

 tion to the fact that, from the nature of the stimuli, the function of 

 hearing must require three mechanisms: (1) A vibratory mechanism; 

 (2) a regulation mechanism, and (3) a mechanism for the perception 

 of sound stimuli. 



Hensen, '63, was the first to advance the idea of the hairs of the 

 hair cells being brushed against the tectorial membrane for the origin 



