302 O. VAN DER STRICHT 



and the surface of the fibrillated zone, where a pecuUar structure, 

 the absence of a membrane, and a lower pressure, promote an 

 exudation of fluid. In this respect a second important factor 

 deserves due consideration, i.e., the shifting of the outer pillars. 

 These structures originally are incorporated within the first row 

 of outer hair cells, and although their extremities remain always 

 fixed, their bodies are pushed inward and inside of the acoustic 

 elements, so that at least a virtual, if not a true space appears 

 below the first row of outer hair cells, between the nucleated 

 portions of the cells of Deiters of the first row (fig. 1, d^) and 

 the outer pillars (op) . This virtual cleft contains a spiral bundle 

 of nerve fibers and represents the future space of Nuel. 



The enlargement of the space of Nuel is doubtless promoted 

 by a third peculiarity — a change in the shape of the outer pillar. 

 When the shifting of the is latter completed, and before any ap- 

 pearance of a cleft, the lateral surface of the rod of Corti is a 

 plane, represented in a vertical or oblique section by a straight 

 line. Along with the lateral extension of the foot upon the 

 basilar membrane (fig. 3, op) and the appearance of the head 

 (figs. 4 and 7, ohd), and by a considerable elongation of the 

 intermediate portion (the future body, fig. 7, opb), which is 

 only possible by virtue of a curvation, the straight line becomes 

 markedly curved, its concavity being turned towards and 

 embracing the cleft. This may be a more important factor 

 than appears at first sight. Indeed, in previous investigations 

 (in press) it has been noted that the shifting of the cells of 

 Deiters may be " completed (that is to say, the sustentacular 

 elements of the first outer row may be situated beneath their 

 corresponding hair cells) before smy appearance of a tunnel 

 space (fig. 9 of the previous paper), or even of the true space of 

 Nuel. In such figures, the original straight line persists, al- 

 though the heads of the outer pillars are large, but the lateral 

 extension of the feet is delayed. 



Structure and transformation undergone by the phalanx processes 

 of the outer pillars. Should any doubt be entertained as to the 

 process of cytolysis along the lateral lower parts of the outer 

 pillars, the structures and the transformation undergone by 



