74 THE GENESIS AND STRUCTURE OF THE MEMBRANA TECTORIA 



slightly elongated enlargement at- its junction with its cell. In the region of the immediate 

 surface of the ridge the interfibrillar matrix does not appear as abundant or so completely 

 produced as in the older body of the membrane. " 



In many figures Hardesty and Prentiss represent the bars, but do not describe 

 them. 



Hold computed 33 to 38 fibrils per each 10(V of the surface of the greater ridge. 

 They are stained red and visible as red granules on sections tangential to the sup- 

 erficial mosaic, each polygon displaying some of them (his figure 3, guinea-pig). 

 Nowhere else does this author mention transverse sections of these elements in the 

 developed membrane, although occasional figures seem to show them. He describes 

 the terminal bars everywhere, but does not attribute to them any importance in 

 the genesis of the membrane. However, investigating the origin of the cupula of 

 the surface of the macula acustica in the rabbit, he states that the reticulum, 

 representing the first stage of development of the cupula, remains attached to the 

 apices of the sustentacular cells by delicate filaments, " wobei sie oft nicht in mitten 

 cler Zellflache, sondern mehr einer Schlussleiste zu sich anheften" (p. 265). He 

 mentions further, beneath the cupula, special filaments in connection with the 

 surface of the sensorial epithelium, and adds: " merkwiirdigerweise sind diese 

 besonderen Faserchen mit den Schlussleisten seitlich verbunden, oft in reicher Zahl 

 von diesen abgehend, welche eine Haarzelle umgreifen." Finally, referring to the 

 filaments of the tectorial membrane in the hen, the chicken, and the pigeon, he states 

 that they " an den freien Flachen der Stutzzellen und oft dicht an den Schlussleisten 

 sich anheften" (p. 275). In spite of these statements, Held accords no importance 

 to the terminal bars in the development of the membrana tectoria. 



Held gives further details of the anatomical substratum of the membrane. 

 In the rabbit he observes a special homogeneous border on the surface of the epithe- 

 lial cells, within which the diplosomes and the terminal bars are inclosed. It is 

 his "Randsaum" and undoubtedly my superficial mosaic. But above it appears 

 another very thin striated border, his "Decksaum," and on page 203 he states: 

 "Die Vorstellungen die ich nur auf Grund dieser Beobachtungen gebildet habe, ist, 

 dass der durch den Rand- und Decksaum ausgezeichnete Epithelbezirk die 

 erste Bildungszone der Cortischen Membran ist." 



Figure 32 represents a portion of the membrana tectoria and the superficial 

 mosaic of the subjacent greater ridge in the vicinity of the future sulcus spiralis 

 (ssp~) partially free and detached from the membrane. It displays some structures 

 very interesting in relation to the fibrillar origin of the membrana tectoria as 

 described by Hardesty and Held. While some fields of the mosaic are clear (/), 

 others are covered by a dark veil (/') or a granular veil stained like the bars. Indeed, 

 many preparations prove that these latter are able to enlarge and extend over the 

 neighboring polygons. But some structures, real filaments (/") derived from the 

 bars, incline and join together over the polygons more superficially where they 

 (the said structures) generate the dense part of the cylinders. If these fibers persist 

 in the walls of the prisms one would have to recognize the fibrillar structure of the 

 walls, but my preparations do not allow me to ascertain with certainty if this be so. 



