476 IRVING HARDESTY 



expressed in the total number of hair cells (extent of membrane) 

 irritated. Obviously some analysis of sound may thus be made 

 in the cochlea. 



The telephone theory differs from the Helmholtz theory in 

 that the latter supposes the basilar membrane composed of fibers 

 of varying length, those of given lengths vibrating in resonance 

 with waves of given vibration frequencies, making entire analysis 

 of sound by the cochlea possible, while the telephone theory as 

 now modified assumes that the basilar membrane vibrates as 

 a whole to every note in such extent as the amplitude of the wave 

 motion and the resistance to its propagation will allow, the audi- 

 tory neurones transmitting to the brain impulses of frequen- 

 cies and intensities corresponding with those of the vibrations 

 concerned. 



Leave is here asked to submit below a modification of the tele- 

 phone theory applied to the tectorial instead of the basilar mem- 

 brane. Siebenmann ('98) seems to have first recognized the 

 importance of the tectorial membrane in the auditory apparatus, 

 noting that it begins in the animal series with the beginning of 

 'musical hearing' and that its absence or deformity results in 

 deafness. He was the first to suggest that it may be thrown into 

 vibration by sound waves. Von Ebner ('02) suggested that the 

 tectorial membrane, especially its free zone, may serve as a 

 mechanism for sympathetic vibrations. Following von Ebner, 

 Kishi ('07) and Shambaugh ('07) attributed powers of resonance 

 to the tectorial membrane but considered it attached to the 

 spiral organ and composed of independently vibratory elements 

 ('lamellae'). 



The anatomical studies undertaken by myself have had to do 

 with the tectorial membrane of the foetal and adult pig and the 

 adult ox, rat and human. Most of them have been made upon 

 cochleae of the pig. My conviction that the tectorial membrane 

 is by form, nature and position the best adapted of the structures 

 in the cochlea for the vibratory activities required in the process 

 of hearing is based upon the following observations: 



(1) The tectorial membrane is strictly coextensive with the 

 spiral organ (organ of Corti). It is developed in company with 



