484 IRVING HARDESTY 



state, it is most inconceivably flexible. In the cochlea while 

 being teased out and in the water under which it is teased, it 

 becomes tangled or adheres to the needle at the slightest touch 

 with most exasperating readiness. In the fresh state especially, 

 it is extremely sensitive to agitations of the fluid surrounding it. 

 This flexibility is much greater in the transverse directions. 

 While wafted about in the water of the dish it manifests sufficient 

 elasticity for its apical turns to resume their normal coil before 

 it settles upon the bottom of the dish. Its thinner basal turn 

 will not do so. It manifests considerably more elasticity in the 

 direction of its width, or against stress applied parallel to its 

 length. Except where it may become twisted, even its very 

 thin axial zone is never found folded upon itself in mounts of the 

 whole membrane nor in pieces of it. With its thin axial zone 

 adherent upon the vestibular lip of the spiral limbus, this latter 

 elasticity is considered sufficient to hold the outspanning zone in 

 its position in proximity to the hairs of the hair cells whatever 

 the position of the head of the animal, especially since the mem- 

 brane manifests a specific gravity but very little greater than the 

 fluid surrounding it. It is suggested that this greater elasticity 

 in its width may allow a delicate spring-like action of the thinner 

 axial part of the outspanning zone, and the adjoining part of the 

 attached zone which overlies the projecting edge of Huschke's 

 teeth {HT, fig. 2, C). Such action may aid in controlling such 

 undulatory motion as the outspanning zone may assume. The 

 form of movement of this zone is suggested to be possibly coarsely 

 represented by that of a flexible ribbon attached along one edge 

 and immersed in water, plus the elasticity and varying pro- 

 portions manifest in the tectorial membrane. 



In constructing the model, the following considerations were in 

 mind. 



The spaces within the cochlea are completely filled with lymph 

 in the normal condition. The vibratory motion imparted to this 

 lymph by the basis of the stapes must be of the form shown by 

 experiment to be propagated in a column of water upon percussion 

 at one end of the column, namely in the form of compression 



