106 J- GORDON WILSON 



(a) a wide meshed plexus in the fibrous tissue, through wh.ich 

 pass most of the fibers which help to form either, 



(b) a subepithelial plexus under the cuticular layer, or 



(c) a subepithelial plexus under the mucous layer. 



From these plexuses the fibers can be traced to various endings, 

 in some cases looping through the plexus they pass into another 

 nerve stem and so reach their endings. 



There are fibers which enter from the tympanic cavity. These, 

 few in number compared with those from the meatus acusticus 

 externus, come from the plexus tympanicus. They ultimately 

 enter the plexuses in the fibrous tissue and under the mucous layer. 



(a) The wide meshed plexus, the Grundgeflecht of Kessel and 

 Deinike, is abundantly distributed throughout the whole fibrous 

 tissue. It consists chiefly of the ramifications and interlacings 

 of the nerves which enter from the meatus externus though fibers 

 also reach it from the tympanic cavity. From it fibers are dis- 

 tributed to the subcutaneous and submucous plexuses, as well as 

 to the endings in the connective tissue. On account of the wide 

 meshes of which the plexus is composed it is easy to follow a 

 single branch for a long distance. Thus in fig. 2 a branch given 

 ofT from a nerve n entering from the meatus externus can be traced 

 through repeated dichotomus divisions till it finally ends in a sim- 

 ple branched ending (c) in the sub-epithelial plexus. In addition 

 to these some very complex endings are seen in the fibrous tissue 

 consisting of an intricate interweaving of a frequently dividing 

 nerve fiber (fig. 3). Into these endings there is often seen entering 

 a second nerve (s), very fine and varicose. I have been unable 

 to identify in man any of the plate-like endings described and fig- 

 ured by Deinike in the horse which lie between the radiating and 

 circular fibers; or those endings figured by myself in the dog lying 

 in the connective tissue in this area. 



In the fibrous tissue near the periphery there are seen several 

 varieties of endings whose size, shape and poorly developed cap- 

 sule enable one to classify as modified vater-pacinian corpuscles 

 (figs. 4 and 5). They lie immediately under the epithelium, no 

 papillae being present in this area or in any part of the membrana 

 tympani. In all these capsulated endings the interlacings are so 



