160 Irving Hardesty 



the resonance theory or of any other theory of hearing. He substitutes 

 the tectorial membrane as being more suited to the purpose, and then, 

 from some rather distorted sections of the cochlea (illustrated with 

 photographs), he assumes that the tectorial membrane is attached along 

 its outer edge to the laminea reticularis of the outer supporting 

 (Hensen's) cells of the organ of Corti, and thus claims that it is held 

 down firmly upon the organ and always at right angles to the auditory 

 hairs. Being also firmly attached along its inner edge, as all admit, 

 Kishi describes and diagrams it as a membrane stretched tautly over 

 the organ from the labium vestibulare of the spiral limbus to the 

 lamina reticularis of Hensen's cells. He then assumes that the length 

 of the fibers composing the membrane ocrresponds throughout to the 

 breadth of the membrane in the respective turns of the coil. Admitting 

 that his assumed absolute length of the fibers (the breadth of the mem- 

 brane) cannot be determined because of shrinkage and distortion pro- 

 duced 'by the technique, he finds, from measurements of the width of the 

 membrane in his sections, that the relative length of the fibers in the 

 apical region is at least three times greater than those of the basal coil. 

 Therefore he assumes that the fibers have different spans, vibrating 

 lengths, in the different regions of the cochlea with all conceivable varia- 

 tions between the longest in the apex and the shortest in the basal end, 

 and thus it is to be inferred that the tectorial membrane is a resonant 

 structure composed of fibers capable of sympathetic vibration to all 

 sound waves of lengths between and including those which may affect 

 its longest and shortest fibers. He realizes that the fibers course 

 obliquely across the membrane, slanting toward the apex, and that, 

 therefore, their actual lengths are greater, especially in the apical region 

 than the width of the membrane as seen in radial sections. 



Against Kishi's conception of the tectorial membrane, three objections 

 may be urged: 



(1) From the processes of development of the membranes, it is very 

 improbable, if not impossible, that any of its fibers in any region extend 

 across the entire breadth of the membrane. 



(2) From the processes of its development, it is probable if not cer- 

 tain that the great majority of the fibers are attached at neither of their 

 ends, but merely lie embedded in the transparent matrix. 



(3) From the studies made here and by others mentioned of prepara- 

 tions as nearly normal as possible, it is concluded that the tectorial mem- 

 brane has but one attachment in life, namely, its inner edge upon the 



