1012 FUNCTIONS OF THE OKGAN OF CORTI. [Book hi. 



One point deserves mention. We saw reason to think (§ 573) 

 that visual impulses cannot be generated in the optic fibres 

 otherwise than through the intervention of the retinal struc- 

 tures ; in the absence of the retina an animal is wholly blind. 

 In pigeons, however, from which the labyrinths of both ears have 

 been entirely removed, a certain apparent power of response to 

 sounds has been observed ; the animals still seemed to hear. 

 And it has been contended that such cases are instances of the 

 mere fibres of the auditory nerve apart from their special termi- 

 nations being sensitive to the vibrations of sound ; it is suggested 



mb 



.i.Kc 



Fig. 182. Diagram of the constituents of the Organ of Corti. (After 



Retzius.) 



A. Inner hair-cells. A', the head seen from above. 



B. Inner, B'. outer rod of Corti, ph. (in each) phalangar process. 



C. The twin outer hair-cell. C.c. cell of Corti, h. its auditory hairs, n. its 

 nucleus, x, Hensen's body. D.c. cell of Deiters, n'. its nucleus, ph. p. its pha- 

 langar process, fil. the cuticular filament, m.b. basilar membrane, m.r. reticulate 

 membrane. 



C. The head of the cell of Corti as seen from above. 



D. The organ of Corti seen from above, i.h.c. the heads of the inner hair- 

 cells, ir.h. the head and phalangar process of the inner rod. o.r.h. the head 

 of the outer rod, with ph. p. its phalangar process, covered to the left hand by the 

 inner rods, but uncovered to the right, o.h.c. the heads of the cells of Corti 

 supported by the rings of the reticulate membrane, ph. one of the phalangse of 

 the reticulate membrane. 



