LAMINA SPIRALIS OF THE COCHLEA. 285 



and also as free or loose. But Claudius has ascertained that 

 the expanded extremity is attached to the lamina pectinata, 

 so that the rod cannot move to and from the membrane, as 

 Corti has supposed. 



It must here be observed, that the first or inner segments 

 of the rods, the " dents apparents " are attached throughout, 

 and from their position and relations belong rather to the 

 structure of the habenula sulcata, than to that of the habenula 

 denticulata. The latter consists, then, essentially of the 

 second and terminal segment described above, connected 

 together by the short " articular " portions. The cochlear rod, 

 properly so-called, consists therefore of two principal segments, 

 the inner segment being connected with one or more ultimate 

 nerve-filaments, and the outer fastened at its external end to 

 the membrane on which it lies. 



Corti has described a thin membrane covered by the 

 epithelium of the labyrinth, and extending from the pro- 

 minent surface of the habenula sulcata somewhat beyond the 

 habenula denticulata. The space between this membrane 

 and the "dents apparents," and also the spiral groove of 

 Huschke, are occupied, according to him, by large transparent 

 nucleated vesicles. Similar vesicles, conceived to be epithelial 

 by their discoverer, occupy the space between the mem- 

 branous lamina spiralis and that portion of Corti's membrane 

 which extends beyond the habenula denticulata. The rods of 

 the cochlea, therefore, according to Corti, move like a series 

 of hammer or pianoforte keys, in a space included between 

 the membrane discovered by him, and the lamina spiralis, 

 usually so-called. Claudius, however, has shown that Corti's 

 membrane extends out to the external wall of the cochlea ; 

 and that the entire space between it and the lamina spiralis, 

 usually so-called, is occupied by vesicular structure. 



The following are the results of observations made for 

 the purpose of verifying the descriptions of Corti, Kolliker, 



