THE LABYRINTH, 679 



liar club -shaped little bodies called the rods of Corti, set 

 up on end, with their big extremities upwards, and leaning 

 against each other at the top a section, therefore, having 

 the appearance of the gable-end of a house. On their 

 outer part are numerous cells of various shapes. The 

 regularity with which the little rods of Corti are arranged 

 has caused them to be compared to rows of keys in a piano. 



In close relation with these rods and the cells outside 

 them, and probably projecting also by free ends into the 

 little triangular canal containing fluid which is between 

 the rods, are filaments of the auditory "nerve. 



The membranous labyrinth corresponds generally with the 

 form of the osseous labyrinth, so far.^as regards the vesti- 

 bule and semicircular canals, but is separated from the 

 walls of these parts by fluid, except where the nerves enter 

 into connection within it. In the cochlea, the membranous 

 labyrinth completes the septum between the two scala, and 

 encloses a separate spiral canal, the canalis membranacea. 

 As already mentioned, it contains a fluid called endolymph ; 

 and between its outer surface and the inner surface of the 

 walls of the vestibule and semicircular canals is another 

 collection of similar fluid, called perilymph : so that all the 

 sonorous vibrations impressing the auditory nerves on 

 these parts of the internal ear are conducted through 

 fluid to a membrane suspended in and containing fluid. 

 The fluid in the seal of the cochlea is continuous with 

 the perilymph in the vestibule and semicircular canals, 

 and there is no fluid external to its lining membrane. 



The vestibular portion of the membranous labyrinth 

 comprises two, probably communicating, cavities, of which 

 the larger and upper is named the utriculus ; the lower, the 

 sacculus. Into the former open the orifices of the mem- 

 branous semicircular canals ; into the latter the canalis 

 membranacea of the cochlea. The membranous labyrinth 

 of all these parts is laminated, transparent, very vascular, 

 and covered on the inner surface with nucleated cells, of 



