MUCOUS MEMBRANE OF THE EUSTACHIAN TUBE. 73 



tube, where trunks of considerable size, which in part run 

 towards the cartilaginous tuba, are met with in transverse 

 section. At a few points the basement membrane, with its 

 ciliated epithelium, is in contact with the loose submucosa; at 

 other points of the mucous membrane, and most frequently 

 beneath the osseous lamella which divides the Eustachian 



Fig. 288. 



Fig. 288. Transverse section of the osseous portion of the Eusta- 

 chian tube. 1, Laminated ciliated epithelium ; 2, conglobate gland 

 tissue ; 3, periosteum ; 4, bone. Magnified 184 diameters. 



tube from the semicanal's tensoris tympanj, lymph corpuscles 

 occur, -closely aggregated in a fibrous reticulum, and we have 

 here that layer of tissue under inspection which has been 

 described under the term conglobate gland substance in the 

 pharynx and in the intestinal canal. It forms a layer, the thick- 

 ness of which varies from 0'056 to 0'040 of a millimeter, and to 

 it is applied the basal membrane with the ciliated epithelium. 

 (See fig. 288.) This has a thickness of 0'028 of a millimeter. 



The pale thin- walled Vessels have still to be mentioned, 

 which traverse the submucosa in a plexiform manner, and in 

 transverse sections of injected ( specimens never contain any of 

 the injection, on which account they have been regarded as 

 lymphatics. All other large spaces and fissures which inter- 

 communicate with one another in the submucosa appear in 

 such injected specimens as blood-conveying vessels. At the 



