HISTOLOGY OF THE MEMBRANOUS LABYRINTH. 



91 



axis of the semicircular canals, give off secondary branches 

 to the periosteum, and are attached to the most diverse points by 

 their gradually expanding extremities. The two sacculi are 

 attached in a very similar manner, except that the finely 

 fibrous connective tissue (the ligamenta labyrinthi sacculo- 

 ruiri) is much more feebly developed at those angles where 

 the sacculi separate from the bone. In the Quadrumana and 

 other Mammals, the labyrinth, which upon the whole is very 

 thin-walled, appears to be as firmly attached as in Man. The 

 connection with the periosteum and the vessels with their 



Fig. 300. 



Fig. 300. Transverse section of an osseous and membranous semi- 

 circular canal of a Rat. 1, Osseous semicircular canal ; 2, plexiform 

 fibrous tissue ; 3, wall of the membranous semicircular canal ; 4, con- 

 nective-tissue corpuscles ; 5, pigment cells. 



delicate investing tissue, is only so far different that the 

 ligamenta labyrintjii canaliculorum appear to be less sharply 

 defined. In the Rat the interior of the osseous canals is every- 

 where traversed by plexiform bands of connective tissue and 

 scattered pigment cells, and is quite half filled by the mem- 

 branous excentric membranous canal, so that here there is quite 

 a different proportion in point of size between the osseous and 

 membranous canals to that observed in Man. No difference 



