ORGAN OF CORTI. 167 



plasmic remains, that is to say, to the upper cells, and forms a 

 portion (the most external cortical portion) of the body of the 

 pillars. The phalangeal process is unquestionably represented 

 by the capitular laminre. It belongs to the residual mass of 

 protoplasm at the base of the pillars (the inferior cells) ; and 

 just as the hair cells are fused with the basilar process, so it 

 is blended with the body of the pillars. This is most distinctly 

 seen in the external pillars, but cannot be overlooked even in 

 the internal ones. The history of the development of the pil- 

 lars, first given by Kolliker, teaches that they are originally 

 conical epithelial cells of the basilar membrane ; but that they 

 really result from the fusion of two cells is evidenced by the 

 residual mass of protoplasm at the capitulum and base, each 

 still retaining, in some instances, its own nucleus. We are not. 

 however, at present in a position to decide whether each pillar 

 proceeds from the union of two originally distinct cells, or, as I 

 consider occurs in the case of the external hair cells, from the 

 fission of one cell with subsequent cuticular metamorphosis of 

 the product of the division.* Each of the external hair cells 

 corresponds, as is obvious from its position, sloped obliquely 

 outwards, to a ring, with the phalanx adjoining it externally. 

 Each phalanx is the cuticular tunic of a hair cell, which lies 

 beneath and is firmly attached to it, just as a tortoise is covered 

 by its shell, and thrusts its head through a ring of bone. Thus 

 the fact is explained that the external phalanges become shorter, 

 and the terminal ones appear as irregular terminal frames, 

 whilst the outermost row of hair cells is less sloped. Long 

 slightly inclined hair cells, as in the Cat, Ox, and Man, furnish 

 a broad lamina reticularis, with elongated meshes ; whilst steep 

 short hair cells, as in Cheiroptera, have a slender narrow 

 reticular plate, with short broad meshes. 



If we put aside the several peculiarities of the internal hair 

 cells, it will be seen that the apparently complicated structure 



* In accordance with the foregoing account, the capitulum of the pillars 

 corresponds to the cilia-bearing extremity of the hair cells. Gottstein and 

 I have long entertained this view, based on our researches, that rudi- 

 ments of cilia exist on the capitula of the pillars (see, for example, fig. 

 334). The fibrous structure of the pillars is also suggestive of the same 

 fact. 



