THE DIGESTIVE TRACT. 587 



tions i. e.j acinous mucous glands in the cavity of the mouth, 

 the throat, the oesophagus, in the lowest portion of the rectum, 

 and in the walls of the duodenum. It also holds the tubular 

 pepsine-glands of the stomach and the tubular intestinal glands 

 in the small and large intestine. The connective tissue forms, 

 especially in youth, a layer of lymph-corpuscles, the so-called 

 " adenoid layer" of myxomatous structure, which is permanent 

 in the villosities of the small intestine, and accumulates here in 

 the solitary follicles and the follicular patches. The mucosa, in 

 many portions, has a circular and longitudinal layer of smooth 

 muscles of its own ; while the canal is everywhere surrounded 



JD 



FIG. 246. LIP OF A CHILD. VERTICAL SECTION. 



E, epidermis; M, rete mucosum ; PP, papillae ; I), derma, with injected blood-vessels M, 

 striped muscle-fibers. Magnified 200 diameters. 



by a circular and longitudinal layer of striated or smooth muscle- 

 fibers, with additional oblique layers in the oesophagus and 

 stomach. The loose fibrous connective tissue, which unites the 

 mucosa to the muscle, is termed the submucous layer, and con- 

 tains, besides a varying amount of lymph-corpuscles, larger 

 blood- and lymph-vessels and numerous nerves in plexiform 

 arrangement, holding scattered or grouped ganglionic elements. 



