Chap, xxiii.] MOUTH, PHARYNX, AND TONGUE. 189 



Saliva obtained from the mouth contains num- 

 bers of epithelial scales, detached from the surface 

 of the mucous membrane, groups of bacteria and 

 micrococci, and lymph-corpuscles. Some of these are 

 in a state of disintegration, while others are swollen 

 up by the water of the saliva. In these there are 

 contained numbers of granules in rapid oscillation, 

 called Brownian molecular movement. 



254. The mucous membrane lining the cavity 

 of the mouth consists of a thin membrane covered on 

 its free surface with a thick stratified pavement epi- 

 thelium, the most superficial cells being scales, more 

 or less changed into horn. 



Underneath the epithelium is a somewhat dense 

 feltwork of fibrous connective tissue, with numerous 

 elastic fibrils in networks. This part is the corium or 

 mucosa, and it projects into the epithelium in the 

 shape of cylindrical or conical papillte. 



According to the thickness of the epithelium, the 

 papillae differ in length. The longest are found where 

 the epithelium is thickest, e.g., in the mucosa of the 

 lips, soft palate, and uvula. 



Numerous lymph- corpuscles are found in the 

 mucosa of the palate and uvula. Sometimes they 

 amount to diffuse adenoid tissue. The deeper part of 

 the mucous membrane is the submucosa. It is looser 

 in its texture, but it also is composed of fibrous con- 

 nective tissue with elastic fibrils. The glands are 

 here embedded ; adipose tissue in the shape of groups 

 of fat cells or continuous lobules of fat cells are here 

 to be met with. The large vascular and nervous 

 trunks pass to and from the submucosa. 



255. Striped muscular tissue is found in 

 the submucosa. Of the lips, soft palate, uvula, and 

 palatine arches, it forms a very conspicuous portion, 

 the sphincter orbicularis, with its outrunners into 

 the mucous membrane of the lips, the muscles of 



