PROPORTIONS OF THE TECTORIAL MEMBRANE 29 



phone theory was appUed to the cochlea as a whole instead of 

 being confined to the basilar membrane. 



Any application of the telephone theory, either to the entire 

 cochlea or to the basilar membrane requires, of course, agitation 

 of the spiral organ and in such a way that the hairs of the hair 

 cells are involved with the basal surface of the tectorial membrane. 

 In other words, the theory must include the possible vibration 

 of the -entire membranous portion of the spiral lamina. 



I do not desire to dispute the possibility that energy imparted 

 to the cochlea by sound waves may throw into vibration the 

 membranous spiral lamina. On the contrary, the possibility 

 seems to me supported in my experiments with the model re- 

 ferred to above, and by studies of the character of the basilar 

 membrane, and especially by the above observation that the 

 cellular part of the spiral organ increases in bulk in passing 

 from its basal to its apical end. Since the base of the stapes 

 imparts the wave motion to the cochlea at its basal end, since 

 the higher pitches are known to be mediated by the basal end 

 of the cochlea, and since sound waves of greater vibration fre- 

 quency (higher pitch) are known to be 'damped out' more readily 

 in overcoming resistance than those of lesser vibration frequency, 

 it seems indeed suggestive that the membranous spiral lamina 

 not only gradually increases in width or bulk but also that its 

 chief load, the cellular spiral organ, itself increases from the 

 basal toward the apical end. But, on the other hand, I beg to 

 emphasize the fact, very evident to me, that the tectorial mem- 

 brane is far more adapted for the vibratory activities required. 

 It is infinitely more flexible than the basilar membrane, or mem- 

 branous spiral lamina, especially when both are in their position. 

 In my previous study I had opportunity to compare the two 

 when both are teased out and found that even then the tectorial 

 membrane as compared with the lamina is as a strip of thin 

 paper compared with a board. The arrangement of the fibei-s 

 in the structure of the tectorial membrane, giving it sufficient 

 elasticity against stress applied longitudinally to enable it to 

 retain its position close upon the spiral organ but giving it prac- 

 tically no resistance to stress applied transversely, renders it 



