ORGAN OF CORTI. 161 



phalangeal process, more slender and somewhat curved, which 

 coalesces with a phalanx of the lamina reticularis lying imme- 

 diately externally and to its side (Gottstein). Moreover, fine 

 short fibrils nerve processes are not unfrequently seen 

 attached to the cell body (fig. 328). 



The basal process runs straight to- the cell body, and then 

 divides into two arms, which embrace the upper nucleus like a 

 pair of forceps (fig. 328, B and (7). Viewed en face, these claws, 

 as soon as the hairs fall off from the cells, appear indistinctly, 

 like a semicircular area, through the ring of the lamina reti- 

 cularis into which the upper (vestibular) end of the cells is 

 inserted. Deiters (13) first noticed this area, and although he 

 was already acquainted with the claws, did not give a correct 

 explanation of it. Kolliker (30) appears to have regarded it as 

 a surface view of the cilia, as he* depicts a semicircular line 

 exactly at the point at which the claws glimmer through, and 

 describes it as a circlet of cilia. The cilia, however, here also, 

 as in the inner hair cells, form. a thick brush, covering the 

 whole terminal surface of the cells (Middendorp, 40, and figs. 

 326 and 329 in this Manual). 



Careful examination of the external hair cells shows that 

 they are really composed of two stalked cells fused into one ; 

 that they are, in fact, true twin or double cells. One of these 

 cells turns its hairy nucleated extremity upwards, and adheres 

 by its peduncle to the membrana basilaris; the other, inti- 

 mately blended with it, lies (turning spirally round it) at the 

 side of the former, and, in opposition to it, has its nuclear end 

 directed downwards (towards the tympanum), and its pedun- 

 cle (phalangeal process) upwards. From the fusion of the two 

 conical cells, the above-described doubly stalked and bi-nucle- 

 ated twin bodies result (fig. 328, BCD; fig. 331, p). The 

 fusion of the two cells is more or less complete in different 

 animals. In Rodents and Cheiroptera the cells can scarcely be 

 detached from one another without, for the most part, effecting 

 their destruction, the several fragments becoming unrecognisa- 

 ble. In Dogs (fig. 328, E) I have occasionally been successful in 

 separating a somewhat mutilated hairy portion from the basal 



* Kolliker, loc. cit., fig. 521. 

 VOL. III. M 



