TERMINATION OF NERVES IN VESTIBULE. 403 



foetal preparations, where the cells retain much of their 

 original epithelial form. 



ftly thorn cells correspond to the cylindrical or fusiform 

 ciliated cells recognised by all. 



The Nerves of the Maculce and Cri&t(^. 



Having thus fully described the nerve epithelium, I now 

 pass on to the nerves themselves, and will afterwards briefly 

 describe the otolith mass covering the acoustic spots. 



The vestibular or posterior division of the portio mollis 

 separates into five branches, one for each of the areas of 

 distribution. In the trunk of this nerve and its branches, 

 but especially in the former, are found fusiform bipolar 

 ganglion cells, corresponding to those of the ganglion spirale 

 of the cochlea, but much larger, those of the latter averaging 

 --y\,-y inch in length, whilst the vestibular cells average 



These five branches pass through the bone to their respec- 

 tive destinations, and the fibres arriving at the membrana 

 propria lose their white substance, entering the nerve-epithe- 

 lium without it. After passing this point there is consider- 

 able difficulty in tracing the nerve filaments, but the later 

 observers are all agreed, as no doubt is the case, that they 

 found a plexus around the deep layer of nuclei, and that 

 »ome of the filaments may be traced directly or indirectly 

 into the ciliated cells. Meyer describes and figures minute 

 nerve filaments forming a plexus and passing up between 

 the cylindrical cells ; the existence of these has not as yet 

 been confirmed by my observations. 



Kiidinger states that he has traced the nerve filament 

 through the centre of the ciliated cell and its nucleus right 

 to the cilium itself; I have sometimes fancied that I could 

 also do this, and certainly there is a central darker portion 

 to be seen in the thorn-shaped cilia. 



The Otolith Mass. 



Covering the acoustic spot is a soft mass of cuticular 

 tissue, into which the cilia project to a certain distance. 

 This mass has an irregular reticulate appearance in prepara- 

 tions, but is evidently of a cuticular nature and analogous to 

 the membrana tectoria of the cochlea, with which it is 

 continuous in the bird according to Hasse. The otoliths are 

 fixed by this mass, being chiefly contained in its outer 

 portion. 



In conclusion, I would observe that, although T am con- 

 fident that my explanation of this structure is the correct 



