THE MIDDLE EAR. 57 



membrana tympani. As to any other relations of the lympha- 

 tics to the epithelium of the mucous membrane, I have no 

 further information than that above given, respecting the 

 figures which make their appearance beneath the epithelium 

 after treatment with solutions of silver and gold. 



The nerves which are distributed in the mucous membrane 

 of the tympanic cavity, and of the membrana tympani, and 

 which may also be followed into that of the Eustachian tube, 

 and into the cells of the mastoid process, proceed from the 

 plexus tympaiiicus, which is an anastomosis between the otic 

 ganglion, the petrosal ganglion of the glossopharyngeal nerve, 

 and the carotid plexus ; that is to say, the superior cervical 

 ganglion of the sympathetic nerve (Bischoff, 3). 



The principal nerve trunks forming the tympanic plexus 

 are composed of medullated fibres, which run in the perios- 

 teum covering the lower and inner walls of the tympanic 

 cavity. They give off small branches to the upper wall, which 

 lie in the stratum of connective tissue subjacent to the epi- 

 thelium, where they form by their intercommunication a wide 

 irregular network. Non-medullated fibres proceed from this 

 last, which form a delicate plexus immediately beneath the 

 epithelium. Ganglion cells of variable diameter, enclosed in 

 capsules, are found either applied to the surface or imbedded 

 in the substance of the principal trunks, as well as of the 

 branches given off from them, and are seen both in their course 

 and at their points of division. They occur either singly or 

 in clusters and groups. In regard to this point I can only 

 corroborate the statements of Pappenheim (32), Kolliker (22) 

 and Krause (23), and maintain the wide distribution of ganglia, 

 in opposition to the observation of E. Bischoff (3), who regarded 

 them as limited to the branches passing from the tympanic 

 nerve to the fenestra ovalis. I may further add, that in 

 the Dog and Cat I have found a few ganglion cells provided 

 with sheaths, lying immediately beneath the epithelium of 

 the mucous membrane where the fine nerve plexuses are 

 situated. 



The mucous membrane in the Dog and Cat presents 

 analogous structural characters to that of Man. The epithe- 

 lium exhibits the same forms, and beneath it there is a fibrous 



