448 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



hair cells (inner and outer) ; (3) supporting cells of 

 Deiters ; (4) the cells of Hensen and Claudius; (5) 

 the lamina reticularis, and (6) a cuticular membrane, 

 the membrana tectoria. 



1 . The rods of Corti form two rows, an inner and an 

 outer. The bases of the two rows are planted on the 

 membrana basilaris, some little distance apart, and 

 the outer ends come in contact so that between the 

 two rows above and the basilar membrane below 

 there is enclosed a triangular tunnel, the tunnel of 

 Corti. This tunnel increases both in height and 

 width toward the apex of the cochlea. The inner 

 rods number nearly six thousand. The outer rods 

 number about four thousand, and are longer than the 

 inner. They are also more inclined toward the bas- 

 ilar membrane and form with it an angle of about 

 forty degrees. 



2. The hair cells are placed on each side of the rods 

 and thus form an inner and an outer set. The inner 

 hair cells form a single row and number about three 

 thousand five hundred, so that each cell is sup- 

 ported by a little more than one rod. Their free ex- 

 tremities are surmounted by about twenty fine hair- 

 like processes arranged in the form of a crescent. 

 Each cell is oval and contains a large nucleus. The 

 lower end is rounded and reaches about 'half-way 

 down the rod, and in contact with this end are the 

 arborizations of the nerve terminations. To the 

 inner side of these cells are several rows of columnar 

 cells that function as supports. The outer hair cells 

 number about twelve thousand, and form three rows 

 in the basal coil and about four rows in the upper two 



