164 THE AUDITORY NERVE AND COCHLEA, BY" W. WALDEYER. 



According to Kolliker (30, 34) and Hensen (27), it is probably to 

 be regarded as a cuticular structure (excretion) formed by the 

 epithelial cells of the crista and of the sulcus spiralis inter- 

 nus. The latter form a thick layer in the embryo, and subse- 

 quently atrophy in the same ratio as the membrane of Corti 

 undergoes development. In Birds, as Hasse (20) states, the 

 membrana tectoria is continued, without any sharp line of 

 demarcation, into the mucous mass in which the otoliths of 

 the lagena are imbedded. 



The most complicated structure of the ductus cochlearis is 

 unquestionably the lamina reticularis of Kolliker, the ex- 

 tremely delicate surface-markings of which I have endeavoured 

 to represent in figs. 326 and 334. This plexiform lamella is 

 composed of a number of annular and finger-biscuit, or digital- 

 phalangeal-like frames, the "annuli" or "rings" of Bottcher 

 (2), and "phalanges " of Deiters (1 2) . The borders of these frames 

 have double contours ; and both the so-called annuli and the 

 phalanges can be obtained in an isolated state. Internally to th 

 arches of Corti (see the illustrations of Deiters, 13) we find only 

 a single series of phalanges and annuli (see fig. 333, in part 

 according to a preparation made by Gottstein), through which 

 last the cilia of the inner hair cells project. These annuli are 

 sometimes continued into a second incomplete reticula,r invest- 

 ing structure, which embraces the heads of the immediately 

 adjoining epithelial cells of the sulcus spiralis internus. Exter- 

 nally to the arches of Corti succeed the greater part of the 

 plexiform lamella, and three or four rows of phalanges and 

 annuli, corresponding to the number of the external hair cells. 

 These, again, are continuous, at the outer border of the organ 

 of Corti, with an irregularly formed cuticular meshwork (the 

 ." terminal frames " of Deiters), which, like the supporting cells 

 of Hensen, is developed on the vestibular surface of the epithe- 

 lium of the zona pectinata, and requires no special description. 

 The annuli and phalanges are arranged regularly in alternating 

 order. Each phalanx is surrounded by four rings, and vice versa* 



A glance at fig. 326 will sufficiently illustrate the statements 



* Strictly speaking, this only holds good if, as will presently be shown, 

 the conception of the phalanges be somewhat extended, and be made to 



