THE ORGAN OF TASTE. 433 



the outer rods of Corti placed upon the membrana basil- 

 aris. The arch rises nearly to the under surface of the 

 membrane of Corti. The rods of Corti are modified 

 epithelial cells, some of which are ciliated. The scalae 

 vestibuli, media, and tympani communicate in the cupola 

 by an opening called the helicotrema. The osseous 

 labyrinth is lined by a delicate endosteum covered by 

 epithelium, and which secretes a thin fluid, called the 

 perilymph. 



THE MEMBRANOUS LABYRINTH. 



The membranous labyrinth is a very delicate serous 

 sac contained within the osseous labyrinth. The mem- 

 branous semicircular canals are about one-third of the 

 diameter of the osseous canals, from which they are 

 separated by the perilymph ; they open into the utricle ; 

 the saccule is connected with the utricle by a delicate 

 canal, and by means of the canalis reuniens communi- 

 cates with the scala media of the cochlea. The mem- 

 branous labyrinth is distended by a thin fluid, the 

 endolymph, which it secretes. On the surface of the 

 utricle and saccule are two small calcareous concre- 

 tions, the otoliths. 



The auditory nerve enters the internal auditory 

 meatus and divides into two branches, cochlear and 

 vestibular ; the latter is distributed to the membranous 

 semicircular canals, utricle, and saccule. The cochlear 

 branch enters the modiolus, and is probably ultimately 

 distributed to the ciliated cells of the organ of Corti. 



THE ORGAN OF TASTE. 



The tongue is a conoidal muscular organ, having an 

 attached base and a free, movable point, or tip. It is 

 contained within the buccal cavity, and while at rest its 



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