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lished a monograph on the vertebrate ear in which I devoted 

 special attention to the anatomy and the histology of the 

 mammalian cochlea, with the result that my discoveries neces- 

 sitated a reconsideration of the prevailing views on the physi- 

 ology of the ear. Since that time I have made several other 

 contributions to the histology of the ear, mainly on the inner- 

 vation of its sense organs. The morphological facts are 

 admitted without question by those who have taken the pains 

 to examine my preparations. Most physiologists and some 

 anatomists, however, have not made use of either the facts or 

 the physiological conclusions which necessarily flow from them, 

 and, so far as I know, they have not troubled themselves to 

 find out the facts. Under the circumstances, and especially 

 because of the excellent human material which I have been 

 fortunate enough to secure and to subject to a careful histo- 

 logical analysis, I am glad to bring before the Association of 

 American Anatomists this statement of a few important facts 

 of cochlear anatomy which are essential to a correct knowledge 

 of the cochlea. 



Membrana Basilaris. 



The membrana basilaris is that part of the connective tissue 

 wall of the cochlear tube which lies under the sense organ and 

 forms its basement membrane. It is far from being the most deli- 

 cate wall of the cochlear tube, for the membrane of Reissner is 

 much thinner and less resistent. The importance of the basilar 

 membrane to previous investigators was due to the dominant 

 Helmholzt-Hensen piano-string theory of tone perception. But 

 it is neither elastic enough nor thin and homogeneous enough 

 to meet the requirements of this physical hypothesis. Accord- 

 ing to my latest observations, the human basilar membrane 

 consists of four layers of fibers, three of which run radially, 

 that is to say, from the free edge of the lamina ossea to the 

 base of the stria vascularis, being continuous with the perios- 

 teum of the former structure and with the connective tissue 

 framework of the latter part. The fourth layer, if it is permis- 

 sible to call a small number of separated fibers a layer, runs at 

 right angles to the other three ; or spirally, with reference to 



