DEVELOPMENT OF THE MEMBRANA TECTORIA 441 



to Coyne et Cannieu ('95), in describing the sections mentioned 

 by Hardesty as confirming the fibrous character of the membrana, 

 they say (p. 286) : 



Cette membrane offre I'aspect d'un reseau, dont les travees serient 

 constituees par une substance amorphe, claire et transparente. Ces 

 travees circonscrivent des cavites polygonales diminuant d'epaisseur 

 a mesure qu'on s'eloigne de I'organe de Corti pour se rapprocher de la 

 protuberance de Huschke. Les cloisons de ces cavites se reunissent au 

 niveau des angles du reseau et forment, en ce point, des espaississments 

 sur toute la longueur de leurs bords de reunion. Ces espaississments 

 sur des coupes radiales de la membrane se montrent sous I'aspect des 

 stries dont nous avons dej^ parle. 



Coyne et Cannieu thus are in agreement with my interpre- 

 tation of the structure and on page 280 state definitely that the 

 membrana is not composed of fibrils imbedded in a homogeneous 

 matrix. Hardesty could not demonstrate by special stains the 

 presence of a matrix which would hold the fibers together. His 

 conclusions are based apparently on surface tiews of the mem- 

 brana in which he saw an apparent fibrillar structure. The ends 

 of the fibers w^hich one may see on the under side of the mem- 

 brana may be interpreted also as the thickenings at the angles 

 of the reticulum shown by Coyne et Cannieu and myself and 

 as drawn by Hardesty himself in figure 9. It is improbable that 

 this structure can be due to shrinkage and coagulation, for the 

 walls of the meshes are sharply defined, clear and refractive, the 

 size of the meshes corresponds to the size of the cells in trans- 

 verse section and the network may be seen attached between 

 cells of the spiral organ when studied in serial sections. 



The accessory tectorial membrane which Hardesty describes 

 as composed of two sets of obliquely crossing fibers he figures 

 as a reticulum with 'diamond' shaped meshes. Its probable struc- 

 ture is that of a reticulum and it may be explained as a thin layer 

 of the membrana tectoria which was left adherent to the spiral 

 organ and later was torn away. It probably represents the 

 reticular membrane or lamina reticularis of the spiral organ which 

 Coyne et Cannieu interpret as a portion of the membrana tec- 

 toria which has remained attached to the cells of the spiral organ. 

 Horizontal sections also explain why the membrana, or portions 



