STRUCTURE OF THE WALL OF THE LABYRINTH. 103 



or to the cartilaginous canal wall is here also the thinnest 

 having a thickness of O'OSO of a millimeter ; whilst that of the 

 thicker part varies from O160 to O120 of a millimeter. It is 

 composed of a firm hyaline matrix, distributed through which 

 are numerous stellate connective-tissue corpuscles, that form, by 

 the anastomoses of their somewhat granular processes, a coarse 

 plexus, exhibiting on close examination, in the Pike, the arrange- 



Fig. 307. 



Fig. 307. Transverse section of the membranous semicircular canal 

 of Esox lucius. 1, Thick free portion of the canal ; 2, thin supported 

 portion of its wall ; 3, tesselated epithelium, becoming columnar on 

 the thick portion of the canal ; 4, cartilage of the labyrinth, with 

 radial fibres and connective-tissue corpuscles ; 5, circular fibres and 

 connective-tissue corpuscles. 



ment displayed in fig. 307. On the thin part of the wall of 

 the canal the fibres run round the lumen of the canal. At the 

 two thickest parts they appear in the form of lines, which 

 traverse the wall in a transverse direction from without 

 inwards. There is no layer of connective tissue on the outer 

 side of the canal ; a pavement epithelium rests on the basement 



