774 



SPECIAL HISTOLOGY. 



Fig. 311. 



under surfaces, and affixed at the outer side, on a projection of the 

 external wall of the cochlear canal. It is a perfectly homogeneous 

 lamella, hut, except at the herders, appears to he very closely rihhed, 

 and thence assumes a fibrous aspect. At its outer edge this lamina, 

 which seems to he opened out in a narrow horder, receives a peculiar' 

 fibrous substance {x) arising from the wall of the cochlea, which there 

 presents a minute osseous ridge (the lamina spiralis accessoria), 

 Huschke ; which Todd and Bowman describe as a cochlear muscle, but 

 in which I can perceive nothing but a form of nucleated connective 

 tissue, whence I shall term it the ligamentum spirale. 



The nerves of the cochlea enter the cavities of the osseous zone from 

 the canal of the modiolus, and there form a close plexus of dark- 

 bordered fibres, 0-0015 of a line in diameter, throughout its whole 

 length, and which, as discovered by Corti, contains, at a very definite 

 spot not far from the border of the zone, an aggregation, at first, 0*1 

 of a line in width, of bipolar, oval, minute (0- 011-0-016 of a line long, 

 '0066-0-0097 of a line broad), and pale ganglion-cells, which it is very 

 probable intercept all the fibres of the cochlear nerves in their course. 

 The dark-bordered fibres proceeding from the external side of 

 these cells, are again disposed in anastomosing, and after- 

 wards in simply parallel, flattened bundles, which become 

 less and less close as they approach the hamulus, so that, 

 upon that process, the fibres may be perceived forming a sin- 

 gle layer, and even separated by interstices. The end of 

 these nerves, in all the parallel bundles and fibres, is always 

 in the same line, but in the first spiral turn will be found 

 nearer to the outer wall of the cochlea than it is higher up. 

 Besides this, there are terminations, also situated between 

 the two plates of the osseous zone, although exactly at its 

 border ; in the second turn, in an extent of 0*02-0-03 of a 

 line, and even outside it, on the under surface of the com- 

 mencement of the hahenula denticulata, consequently within 

 the scala tympani ; in the third half turn, lastly, they appear 

 in the form of a nervous border, 0-08-0-09 of a line broad, 

 also on the under surface of the hahenula sulcata. The 

 actual termination of the nerve-fibres which are reduced to 

 O'OOl of a line in diameter, appears to me, as well as to 

 Corti, to take place by their first becoming pale, and still finer, and 

 afterwards ceasing — and I must here express myself as decidedly 

 opposed to the notion of the existence of loops.* 



Fig. 311. — Bipolar ganglion-globules from the zonula ossco of tlie lamina spiralis of the Pig, 

 magnified 350 diameters. After Corti. 



• [More recent researches have induced Prof. Kcilliker to alter materially his views on 

 the termination of the cochlear nerve, and indeed of the structure of the cochlea itself. As 

 the result of careful investigations in the Ox, Cat, Pig, Rabbit, and in Man, he found that 



