The Nature of the Tectorial Membrane 171 



torial membrane, and to be stimulated more strongly by undulations of 

 greater amplitude. Either relation (that is, if the hair cells do not lie 

 in the same plane), would be a factor in determining the number (and 

 also the intensity) of the stimuli applied to a unit area of the organ of 

 Corti. Such conditions are merely suggested by the slides. Though 

 constant in my preparations, the grouping may be artifact and may mean 

 nothing at all. 



As evident in the above pages, I have entered very lightly into an 

 application of the laws of physics to the anatomical role suggested for 

 the tectorial membrane. Many features must be subjected to further 

 anatomical investigation and must receive further substantiation before 

 a wise application of the known can be made. For the same reason, the 

 physiological phase of the question, which, based upon the many audi- 

 tory phenomena, could be prolonged indefinitely, is touched upon but 

 little. Just how far the cochlea, in itself, takes part in the analysis of 

 sound is the difficult question: In the physiological literature the 

 cochlea is spoken of as analyzing^ noticing, appreciating phase, distin- 

 guishing and perceiving tones, etc. It is well known that several waves 

 may pass, in the same direction, simultaneously through a medium. In 

 the cochlea, acting as above suggested, their resulting stimulation of 

 the auditory hairs would be somewhat segregated as to pitch. A 

 mixture of sounds of different qualities but of approximate pitch would 

 act upon approximately the same area of the organ of Corti, complicate 

 the process and probably be interpreted as "noise/' The matter of the 

 finer analysis of sound is no doubt almost wholly cerebral. It certainly 

 is largely a matter of education. It is of course probable that cochlese, 

 as other organs of the body, may differ as to their anatomical excellence 

 in different individuals. I wish to suggest that most of the phenomena 

 of hearing which are actually peripheral may be explained on the basis 

 of the relationships suggested. 



Impulses borne by the cochlear division of the acoustic nerves are 

 conveyed to given localities of the cerebrum. Probably any stimulus 

 aroused in these fibers gives rise to sensations of sound. Gray, '00, 

 reports a case of deafness and "singing noise in the ear'' in which the 

 post-morten examination showed all the divisions of the ear to be in 

 perfect condition, but, on further search, a tumor was found in the 

 medulla oblongata encroaching upon the entering trunk of the acoustic 

 nerve. Tinnitus aurium could be produced not only in this way, but, 

 if produced temporarily, or permanently as sometimes happens, by a 



