160 THE AUDITORY NERVE AND COCHLEA, BY W. WALDEYER. 



these dimensions increase towards the hamulus. (For more 

 precise details the reader is referred to Hensen, 27.) 



The inner portion of the roof of the arches of Corti supports, 

 as its most essential structure, the single spiral row of the 

 inner hair cells (fig. 331, i; figs. 334 and 335). These are of 

 a compressed conical form, and the strongly defined nucleus 

 lies nearly in the centre of the very delicate cell body. This 

 last is prolonged towards the tympanic scala in the form of a 

 long process, which is lost in a layer of small cells, the granule 

 layer (fig. 335, A). The ends of the hair cells directed towards 

 the scala vestibuli are embraced by the accessory laminae of 

 the capitula of the internal pillars (fig. 333, i Ji), and support 

 upon their cuticular covering a close pile of strong rod-like 

 hairs, which appear to be of a very resistent nature. The epi- 

 thelial cells of the sulcus spiralis immediately adjoining the 

 hair cells are columnar, and alternate with them (figs. 326 and 

 331). They cover the just-mentioned granule layer. 



The relations of the cells lying at the outer side of the arch 

 are less obvious, and this is especially true of the hair cells 

 the cells of Corti of authors which are amongst the most difficult 

 objects of research in the cochlea. In describing these I shall 

 follow the account given by Gottstein at the Innsbruck Scien- 

 tific Congress of 1869. The external hair cells are arranged in 

 three or four spirally running parallel series, but so that the 

 several cells of each row alternate with great regularity with 

 those of the immediately adjoining rows (fig 326). Each row 

 contains about as many cells as there are external pillars. 

 According to Gottstein, the cells have two nuclei an upper 

 smaller one, and a second larger one, situated in the lower part 

 of the cell. Two thick processes are given off from the cell 

 body near the lower nucleus ; the straight basal process, which 

 is firmly attached to the basilar membrane by a small triangu- 

 lar swelling (fig. 328), forming the stronger and longer, and the 



base. E, Isolated twin-cones from the Dog, magnified 800 diameters. 

 Two kinds of cells, m and n, are at first in immediate connection, so 

 that the pointed extremity of n runs into the cell protoplasm of m, 

 the hairs being directed upwards. The phalangiform processes, 6, are 

 still in connection with the phalanges, h ; g, cuticular margin of the 

 rings with hairs ; a c d, as before. 



