The Nature of the Tectorial Membrane 153 



(1) A mixture of notes of closely approximate beats, even having 

 varying intensity, cannot be analyzed by the auditory apparatus; rather, 

 only the maximum stimulus in the mixture is perceived. Gray, '00, 

 attempts to obviate this with a modification of the resonance theory, in 

 which he compares the sense of hearing with that of touch. He sup- 

 poses that the basilar membrane does not vibrate as to its individual 

 fibers, each in response to a given note, but rather in areas of its extent 

 for each note, and thus he assumes that the mixture of approximate 

 notes involves a given small area of the basilar membrane from which 

 only the maximum stimulus is appreciated by the brain, all others of 

 the mixture being neglected, just as when a small area of the skin is 

 stimulated by a very bluntly pointed instrument and the "mind only 

 pays attention" to the point of maximum stimulation; or, just as when 

 two points on the skin, close enough together, cannot be distinguished 

 from a single point when stimulated simultaneously. Evidently this 

 modification also obviates the requirement of the resonance theory that 

 each arch or pair of rods of the organ of Corti, as well as each fiber of 

 the basilar membrane, must be able to move or vibrate independently. 



(2) It is generally conceded that sensations of "noise" as distin- 

 guished from the perception and analysis of tones cannot be adequately 

 explained by the resonance theory. Hensen, '07, has recently put forth 

 an elaborate modification of this theory in which he tries, among other 

 things, to account for this inadequacy. It is unnecessary here to discuss 

 his ingenious paper further than merely to state that he retains the 

 assumption that the basilar membrane is composed of fibers with the 

 power to vibrate individually, allowing that probably several adjacent 

 fibers, being of approximately the same length, may vibrate together 

 with the respective note. To do this, he finds it necessary to add the 

 assumption that the cochlea mediates only musical tones, and he calls it 

 the "musical organ." This makes it needful for some other structure to 

 mediate sensations of noise, etc., and for this he finds the cristas of the 

 semi-circular canals and the maculae acusticse adequate. 



Wliile, strictly speaking, the two objections or inadequacies cited 

 are anatomical as well as physiological, there are some which may be 

 considered more purely anatomical, and therefore physical, objections 

 to the resonance theory. 



From the nature of available information, the intangibility of the 

 apparatus, it has been the rather common custom in discussing the 

 physiology of hearing, to first assume the existence of anatomical 



