46 THE EXTERNAL AND MIDDLE EAR, BY J. KESSEL. 



epithelium, and therefore along the manubrium and towards 

 the tendinous ring. Here they frequently increase in size and 

 number at the expense of the brown-coloured masses,, and form 

 light spaces communicating with each other. 



I found in the clear spaces of the membrana tympani of the 

 Dog and Cat, as in that of Man, strongly looped fine lines, 

 thickened at certain points, which, becoming progressively 

 finer by dichotomous division, run outwards in all directions, 

 and consequently into the brown masses. (See fig. 283.) 

 Similar markings, indicating the presence of serous canals, have 

 been described by Koster,* and used by him as corroborating 

 his view, that the serous canals are formed of epithelial cells. 

 The light spaces are here and there seen bounding one or both 

 sides of the vessels, and communicating with the attenuated 

 extremities of adjoining serous canals. What relation exists be- 

 tween the serous canal system and the epithelium of the mucous 

 membrane, or rather between it and the above-described openings 

 between the epithelial cells, I have not hitherto been able to dis- 

 cover; and shall here only mention the interesting fact in a phy- 

 siological point of view, that in the Dog I effected the most 

 beautiful and complete injection of the lymphatics of the mem- 

 brana tympani from the tympanic cavity, by the method first 

 adopted by von Recklinghausen, and subsequently by Ludwig 

 and Schweigger-Seidel, in the case of the diaphragm. It follows, 

 therefore, from the above injection experiment showing the 

 arrangement of the lymphatic system, that every alteration of 

 tension of the membrana tympani must exert a suction action 

 on the contents of the tympanic cavity, and eventually also aid 

 the propulsion of the same within the lymphatics. 



The nerves of the membrana tympani are distributed like 

 the vessels in the cutis, membrana propria, and mucous mem- 

 brane. The larger trunks accompany the principal blood- 

 vessels, divide like these, and frequently intercommunicate like 

 the capillaries. They extend with the latter into the regions 

 supplied by them, and consequently form close plexuses both 



* Ueber die feinere structur der menschliche Nabdschnur. " On the 

 Minute Anatomy of the Umbilical Cord of Man." Inaugural Dissertation. 

 Wiirzburg, 1868. 



