166 THE AUDITOEY NERVE AND COCHLEA, BY W. WALDEYER. 



veloped phalanges are deficient (see fig. 326), and thus the ter- 

 minal frames of Deiters are produced. 



Every annulus is occupied with the base of the hair cell 

 belonging to it. The frames of the annuli are continuous 

 with the frames of the adjoining phalanges, so that on 

 isolation of a phalanx or of an annulus, fragments of the 

 adjoining annuli (or phalanges) are always carried away, just 

 as it is impossible to isolate a single mesh of a net without 

 destroying the several adjoining meshes. Moreover, the pha- 

 langeal frames are occupied by a delicate membrane, which is 

 nevertheless sometimes destroyed, so that only the bare frame- 

 work remains. 



No similar morphological description of the external surface 

 of the lamina reticularis has hitherto been given, apart from 

 the correct statement made by Kolliker, that it constitutes a 

 cuticular cover to the organ of Corti. A right comprehension 

 of this structure, which at first sight appears so complicated, 

 and at the same time a correct understanding of the arches and 

 organ of Corti, only becomes possible when all these parts are 

 considered in their mutual relations as forming one whole. 



If we travel over the organ of Corti, from within outwards, 

 and for the sake of simplicity take that of Man, in whom the 

 hair cells are very numerous, we find six rows of cells ar- 

 ranged one behind the other, and regularly alternating : the 

 internal hair cells, the internal and the external pillars of 

 Corti, and three rows of external hair cells. The regular alter- 

 nation of their disposition is only disturbed by the varying 

 numbers of the internal hair cells and pillars. 



Close examination of the pillars of Corti soon renders it 

 apparent that they correspond in structure to the external hair 

 cells. Each pillar is chiefly composed of a cuticular metamor- 

 phosed twin-cell, of which one part, the nucleated basis, is turned 

 towards the membrana basilaris, whilst the other is directed 

 towards the lamina reticularis. The nucleated portion of this 

 last part is situated at the capitular laminae of the pillars, where 

 we have already (p. 154, et seq.) noticed their nucleated proto- 

 plasmic remains, whilst they have long been recognized at the 

 bases of the pillars. Moreover, the two processes are present. 

 The basilar process belongs to the upper portion of the proto- 



