166 Irving Hardest}^ 



body, one of the resulting complications will be a lowering of the vibra- 

 tion frequency of that part. Should the tectorial membrane be consid- 

 ered a vibrating body carrying a load so distributed as to gradually 

 increase toward its apical end, then its vibration period or frequency 

 must decrease as this end is approached. Therefore, it is possible that 

 the thin, narrow basal coil of the tectorial membrane may be sufficiently 

 affected by waves of high frequency to stimulate the auditory hairs 

 when other portions of the membrane are not. Several waves, of course, 

 may pass in a medium simultaneously in the same direction. 



This idea suggests a sort of resonance quality in the tectorial mem- 

 brane when the latter is considered as a whole, and thus it is not fully in 

 accord with the idea originally suggested in applying the telephone theory 

 to the basilar membrane. It is slightly analogous to some of the features 

 of Waller's and Meyer's modification of the telephone theory. 



(3) The natural consistency of a strip attached along one edge deter- 

 mines in considerable measure the extent and form of movements induced 

 in it by wave motion in the medium surrounding it. The basal end of 

 the tectorial membrane, being narrower and thinner, though of the same 

 material, is more flexible than the end at the apex. Therefore, it must 

 offer less resistance to waves of high frequency (is more easily crumpled 

 into abrupt and frequent folds) than the thick apical end. The viscosity 

 of a vibrating body, while it may affect the vibration frequency (pitch) 

 but little, aids materially in causing the amplitude of vibration, the 

 excursion or intensity of movement of the body, to gradually decrease 

 and dwindle away as the waves pass along the body. It is therefore 

 possible that waves of high frequency are capable of throwing the thin 

 basal coil of the tectorial membrane into waves of considerable excursion 

 or amplitude, while, as they pass along toward its apical end, they may 

 be gradually absorbed in overcoming the inertia of the membrane ; first, 

 becoming too faint to throw it into vibrations, or folds, of their fre- 

 quency and of sufficient amplitude to agitate the auditory hairs below, 

 and finally, as the broad, thick end is approached, a region is reached 

 in which the waves of high frequency wholly dwindle away. 



In the same way, for the above reasons, it may be suggested that 

 waves of lower frequency than those which sufficiently agitate the basal 

 end of the membrane only, can, according to their frequency or length, 

 affect respectively the remaining regions sufficiently to stimulate the 

 auditory hairs, because such longer waves travel farther in the given 

 medium, are less rapidly overcome by friction of the walls of the scala 



