NERVES AND EPITHELIUM OF AMPULLA AND SACCULI. 



membranous canals; that is to say, it never appears as a 

 tesselated, but always as a transitional form of epithelium. 



If the epithelial layer be broken up, the presence of several 

 cell-forms may be demonstrated in it, in Man, Mammals, and 



Fig, 312. 



Fig. 312. Horizontal transverse section through the vestibule and 

 sacculus rotundus of the human foetus. 1, Cartilage ; 2, nerves in 

 the median wall of the vestibule ; 3, crista vestibuli ; 4, nerve epi- 

 thelium in the sacculus rotundus ; 5, auditory hairs ; 6, transition of 

 the nerve epithelium into 7, the flatter columnar epithelium ; 8, the 

 lateral wall of the sacculus rotundus ; 9, utriculus, with the nerve 

 epithelium ; 10, tesselated epithelium of the utriculus. 



Fishes. In the first place, there are elongated columnar cells 

 of tolerably equal thickness, with a large nucleus at the central 

 extremity. One end of these cells is broad, the other runs out 



VOL. III. I 



