Wilson, Membrana Tympani. 465 



distributing center for the epithelial plexuses and for the various 

 varieties of endings. 



From the ground plexus in the membrana tensa fibers pass off 

 to form very intricate and dense subepithelial plexuses directly 

 under the cuticular and mucous epithelium, but chiefly the former. 

 From the subcuticular plexus fibers pass into the epidermis (Fig. 

 11). Some of these fibers may travel for a considerable distance 

 among the deeper epithelial cells before they end, interlacing and 

 surrounding them so that they may be said to form an interepithe- 

 Hal plexus. They end near the surface as fine interepithehal 

 points or bulb-like bodies probably from a distension of their con- 

 tents by the dye. No other endings are to be seen in the epithe- 

 lium but these fine or bulb-like structures. 



In the fibrous tissue the plexuses are abundant and intricate, 

 and the fibers may show frequent divisions and interlacings. The 

 following varieties of endings can be distinguished: 



{a) The nerve fiber breaks up repeatedly into a number of fine 

 fibrils which interlace and end as fine points or bulbs close to con- 

 nective tissue cells (Fig. 9). 



{h) A fiber divides into two branches each of which, after 

 making several corkscrew turns, again divides; the resulting 

 branchings surround a cell which stains like a connective tissue 

 cell (Fig. loa); or a fiber may divide into several fibrils which, 

 after taking several corkscrew turns, form a long narrow plexi- 

 form ending between the connective tissue cells (Fig. lob). 



{c) A nerve breaks up into branches each of which ends in 

 arborizations. These are especially abundant near the malleus 

 and at the limbus (Figs. 7 and 8). 



The nerves which enter from the tympanic cavity are relatively 

 few in number and end in an epithelial plexus under the mucous 

 membrane. This submucous plexus also receives branches from 

 the ground plexus. As mentioned by Jacques and Calamida, 

 no ganglion cells are present. 



One cannot but note how analogous the distribution of the 

 nerves in the membrana tympani is to that of the cornea. Here 

 also we find a zonular plexus (plexus annulaire); a ground plexus 

 (plexus fundamental) occupying the whole stretch of the cornea 

 near the surface; and a plexus subepithelial and interepithehal 

 with bud or point-like endings.^ One is tempted to carry the 



' PoiRiER et Charpy, vol. 5, p. 1040. 



