222 SPECIAL SENSES. 



Figs. 18 and 19, the latter figure, however, exhibiting other 

 structures which enter into the constitution of the organ of 

 Corti. It will be remarked that a small nucleated body is 

 attached to the base of each pillar. At the summit, where 

 the internal and the external pillars are joined together, is a 

 delicate prolongation, directed outward, which is attached to 

 the covering of the quadrilateral canal. 



The above description comprises about all that is defi- 

 nitely known of the arrangement of the pillars, or rods of 

 Corti. They are nearly homogeneous, except when treated 

 with reagents, and are said to be of about the consistence of 



FIG. 18. 



The two pillars of the organ of Corti : 



A, External pillar of the organ of Corti. l,body, or middle portion; 2, posterior extremity, 

 or base ; 8, cell on its internal side ; 4, anterior extremity ; 5, convex surface by which 

 it is joined to the internal pillar ; 6, prolongation of this extremity. 



B, Internal pillar of the organ of Corti. 1, body, or middle portion ; 2, posterior extremity ; 

 3, cell on its external side ; 4, anterior extremity ; 5, concave surface by which it is joined 

 to the external pillar; 6, prolongation, subjacent to that of the external pillar. 



C, The two pillars of the organ of Corti, united by their anterior extremity, and forming an ar- 

 cade, the concavity of which presents outward. 1, 1, body, or middle portion of the pillars ; 

 2, 2, posterior extremities; 3, 3, cells attached to the posterior extremities; 4, 4, ante- 

 rior extremities joined together; 5, terminal prolongation of this extremity. (&APPEY, 

 Traite tfanatomie, Paris, 1811, tome iii., p. S49.) 



cartilage. 1 They are closely set together, with very narrow 

 spaces between them, and it is difficult to see how they can 

 be stretched to any considerable degree of tension. The arch 

 is longer at the summit than at the base of the cochlea, the 

 longest rods, at the summit, measuring about -^j- of an inch, 

 and the shortest, at the base, about -g-J-^- of an inch. 2 As we 



1 QUAIN, Elements of Anatomy, London, 1867, vol. ii., p. 765. 



2 The measurements given above are taken from a recent article by Pritchard, 



