452 



THE ALIMENTARY CANAL 



[CH. XXVII. 



thicker. Both alike consist of bundles of unstriped muscle supported 



by connective tissue. They 



are well provided with lymphatic 

 vessels, which form a set distinct 

 from those of the mucous mem- 

 brane. 



Between the two muscular coats 

 is a nerve-plexus (Auer bach's plexus) 

 (fig. 380), similar in structure to 

 Meissner's (in the submucous coat), 

 but coarser and with more numerous 

 ganglia. 



(3) Between the mucous and 

 muscular coats is the submucous coat, 

 which consists of connective tissue in 

 which numerous blood-vessels and 

 lymphatics ramify. A fine plexus, 

 consisting mainly of non-medullated 

 nerve-fibres, Meissner's plexus, with 

 ganglion cells at its nodes, occurs 



in the submucous tissue from the stomach to the anus. 



(4) The mucous membrane is the most important coat in relation 



to the function of digestion. Its general structure resembles that 



Fio. 379. Horizontal section of a small frag- 

 ment of the mucous membrane, includ- 

 ing one entire crypt of Lieberkiihn and 

 parts of several others. The glands are 

 separated by loose adenoid tissue. 



Fio. 380. Auerbach's nerve-plexus in small intestine. Ganglion-cells are imbedded in the plexus, the 

 whole of which is enclosed in a nucleated sheath. (Klein.) 



of the stomach, and, like it, is lined on its inner surface by columnar 

 epithelium. Adenoid tissue (fig. 379) enters largely into its construc- 

 tion ; and on its deep surface is the muscularis mucosce (ra, fig. 382), 



