118 Irving Hardesty 



has to observe its Ijehavior closely to perceive its elasticity. The elas- 

 ticity ajjparent may be compared with that of a very thin strip of set 

 gelatin immersed in cold water. If not injured by stretching or badly 

 tangled, a piece of the tectorial membrane, as it floats around in a dish 

 of unagitated salt solution, Avill gradually approach the coiled form 

 similar to its natural shape when in the cochlea and thus come to rest 

 upon the bottom of the dish. In case of whole membranes, or of longer 

 pieces, the portion representing the upper or apical coils of the cochlea 

 will assume the natural form more quickly than the other end or the 

 portion from the basal coil, because of the fact that the membrane 

 is thickest and broadest at the summit, gradually decreasing in size 

 toward the base. Twists are far more common and more serious in 

 the more slender region of the basal coil, and unless they disappear 

 before the membrane reaches the bottom of the dish, the basal coil 

 never assumes its natural form and thus pieces may come to rest with 

 the apical coils well formed while the portion from the basal coils may 

 be irregular or scarcely coiled at all. The more evident elasticity of 

 the summit end of the membrane is explained as being due merely to 

 the greater bulk of this end. 



Whole membranes and pieces removed intact from the attachment 

 upon the lal)ium vestibidare, unless containing twists, always come to 

 rest flat upon tlie bottom of the dish, the under surface either upward 

 or downward, notwithstanding the fact that the inner zone of the 

 meml^rane removed from the labium vestibulare is very thin and tapers 

 to an edge. This behavior, coupled with the fact that the direction of 

 its greatest flexibility is transverse to the long axis of the membrane, 

 together with its shape in transverse section, indicates that its greatest 

 elasticity must ])e in the direction opposed to longitudinal rather than 

 transverse stress. Elasticity in this direction can be largely instru- 

 mental in inducing the membrane to resume its natural shape when in 

 fluid, and the membrane, being laterally attached along the inner zone, 

 elasticity in this direction must tend to maintain the outer zone in its 

 position above the organ of Corti. 



Experiments, intentional and accidental, in stretching the tectorial 

 membrane longitudinally indicate a small amount of elasticity opposed 

 to such force. Pieces of the fresh membrane in salt solution, if 

 stretched very slightly indeed will return to apparently their original 

 thickness; if stretches more strongly, they will suffer attenuation, part 

 of which becomes permanent; if stretched further, they may be drawn 



