III. 



THE MEMBRANOUS LABYRINTH. 

 BY PROFESSOR RUDINGER, 



OF MUNICH. 

 1. TOPOLOGICAL AND HlSTOLOGICAL ACCOUNT. 



IN consequence of experimental observations, some doubt has 

 been thrown on the functional importance of the membranous 

 labyrinth for the faculty of hearing ; it must still, however, 

 be considered an integral part of the inner ear, by virtue of 

 its being the supporter of the acoustic percipient apparatus. 

 Its topographico-histological relations present numerous dif- 

 ferences in the various classes of animals. In many Inverte- 

 brata, as in Mollusca and Crustacea, a vesicular structure 

 appears as the representative of the labyrinth, which is usually 

 seated on the nerve centre, or on one of its branches. In the > 

 Achetidse and Locustidse, amongst Insecta, it is placed nearj 

 the knee-joint; and in the Acrididse, over the origin of the last) 

 pair of feet. In almost all Vertebrata the membranous laby- 

 rinth forms a division of the auditory apparatus, that is found 

 to be enclosed more or less completely in a cartilaginous or 

 osseous capsule, of which it forms an attenuated protrusion. 

 The elongated sac, or utricle,, with its ampullae and semi- 

 circular passages, as well as the more rounded sacculus, are in 

 direct contact with the osseous or cartilaginous capsule, and 

 are not, as has hitherto been erroneously believed, completely 

 surrounded by fluid (perilymph). 



These topographical relations of the labyrinth are already 



i \ f - ( ltv ^ 



