ORGAN OF CORTI. 223 



before remarked, the relations between the pillars and the 

 terminal filaments of the auditory nerves are not definitely 

 settled. 



In addition to the pillars just described, various cellular 

 elements enter into the structure of the organ of Corti. The 

 most important of these are the inner and the outer hair- 

 cells. The inner hair-cells are arranged in a single row, and 

 the outer hair-cells, in three rows. Nothing definite is known 



FIG. 19. 



Vertical section of the organ of Corti of the dog. Magnified 800 diameters. 

 a-b, t homogeneous layer of the basilar membrane ; . tympanic layer, with nuclei, granular cell- 

 protoplasm, and connective tissue; tfj, tympanic lip of the crista spiralis; c, thickened por- 

 tion of the basilar membrane : d, spiral vessel ; e, blood-vessel ; / bundle of nerves ; gr, epi- 

 thelium: i. inner hair-cell, with its basilar process, k; Z, head-plate of the inner pillar; ?, 

 union of the two pillars; n, base of the inner pillar; o, base of the outer pillar; p, q, r, 

 outer hair-cells, with traces of the cilia; #, bases of two other hair-cells; , Hensen's prop- 

 coll ; /-,, lamina reticularis ; w, nerve-fibre passing to the first hair-cell, p. (WALDEYER, in 

 STEICKEB, Handbucli der Lehre von, den Geweben, Leipzig, 1871, S. 944.) 



of the function of these cells. The relations of these parts 

 are shown in Fig. 19, which is rather complex, but, on care- 

 ful study, gives a good idea of the arrangement of all of the 

 structures which compose the organ of Corti. It is supposed 



already referred to. At the base of the cochlea, the two sets of rods are about 

 equal in length. From the base to the apex, both sets, outer and inner, pro- 

 gressively increase in length, and the outer rods become the longer, so that, near 

 the apex, they are nearly twice the length of the inner. 

 145 



