472 IRVING HARDESTY 



of 1915 describes some observations upon adult cochleae, chiefly 

 those of the adult hog. 



The purpose of this paper is to describe a model and to mention 

 some of the results obtained with it suggesting the action of the 

 tectorial membrane when actual sound waves are appUed to the 

 tympanic membrane. It is thought advisable to precede this 

 description by a brief resume of the anatomical observations 

 made in previous papers which have led to the conviction that 

 the tectorial membrane is the structure best adapted for the 

 vibratory activities required. The model lays no claim to com- 

 pleteness of plan. Both its form and excellence of construction 

 leave much to be desired. Consideration of only the few simpler 

 and most evident of the results obtained with it will be under- 

 taken. Many of the phenomena it presented appeared so mixed 

 and complex in the physics involved that, considering the great 

 coarseness and imperfection of the model as compared with the 

 cochlea itself, attempts to interpret them seemed needless as well 

 as almost hopeless. Some figures are given for review of certain 

 of the anatomical features mentioned as well as figures to illus- 

 trate the construction of the model. Citations to most of the 

 literature consulted are given in the prevjious papers and but 

 few of these will be repeated here. 



RESUME OF THE THEORIES OF HEARING AND OF OBSERVATIONS 



UPON THE SUPPOSEDLY VIBRATORY STRUCTURES 



RELATED TO HEARING 



It is considered established (1) that the cochlea is the essential 

 organ of the peripheral part of the auditory apparatus, that it 

 contains the neuro-epithelium in which auditory impulses are 

 aroused and is generally thought to be so constructed as to be es- 

 pecially capable of serving, in conjunction with the central nervous 

 system, in the analysis of sound; (2) that the auditory impulses 

 imparted to the fibers of the cochlear nerve are aroused in the 

 hair cells of the neuro-epithelium (organ of Corti) by impingement 

 of the hairs of the hair cells against the basal surface of the 

 tectorial membrane, and that the impingement results from 

 vibratory motion induced by that form of atmospheric disturb- 



