244 



TWENTY-THIRD LECTURE. 



uncertainty, an extremely complicated nomenclature has also 

 been developed.* 



The osseous portion of the spiral plate contains the expan- 

 sion of the cochlear nerve. At its peripheral exit its bundles 

 of fibres meet the so-called organ of Corti (Fig. 198, //). 



7>9 * 



mkmSSiW^i 



Fig. 198. — The Corti's organ of the dog in perpendicular section : a, b, homogeneous stratum of the 

 membrana basilaris ; u, vesicular stratum : 7', tympanic stratum with nuclei and protoplasma ; 

 a, labium lympanicum of the crista spiralis : a, continuation of the tympanic periosteum of the 

 lamina spiralis ossea ; c, thickened commencing portion of the membrana basilaris, together with 

 the place of section, //, of the nerve d, and e blood-vessels ; _/, the nerve: g, epithelium of the 

 sulcus spiralis externus ; i, inner hair cell with the basal process, k, surrounded by nuclei and pro- 

 toplasma (of the " granule stratum "), into which the nerve fibres radiate : », base or foot of the inner 

 pillar of the Corti's organ; m, its "head piece," connected with the same part of the outer pillar, 

 the lower part of which is wanting, while the next following pillar o, presents the middle part 

 and the base : /, q, r, the three outer hair cells ; z, a so-called supporting cell of Hensen ; L, lamina 

 reticularis ; w, nerve fibre terminating at the first of the outer hair cells. 



In a transverse section it forms a conical elevation of the 

 membranous base of the cochlear canal. It is hollow in its 

 interior, and forms collectively, by the cochlear convolutions, a 

 spiral tunnel. Its structure is infinitely complicated. 



We here meet with a double row of convergent ascending 

 "pillars" {n, m f o) which meet each other at the top of the Cor- 

 tian organ. There are two of the " external pillars " (o) to 

 three of these internal elements (/i, ni). At their base we 

 meet with cell rudiments. 



A further diversity is induced by the epithelial cells of the 

 cochlear canals. They become from within outwards (that is 

 from the axis of the cochlea towards its convex external arch) 



* The cochlear canal has been the object of extraordinarily extensive labors on 

 the part of Reissner, Claudius, Boettcher, Schultze, Deiteis, Hensen, Waldeyer, 

 Gottstein and others. 



