454 



THE ALIMENTARY CANAL 



[CH. XXVII. 



general surface of the mucous membrane, is surmounted by a bright 



striated border (see pp. 25-27). 



Immediately beneath the basement membrane there is a rich 



supply of blood-vessels. Two or more minute arteries are distributed 



within each villus ; and from their capillaries, which form a dense 



network, proceed one or two small 

 veins, which pass out at the base of 

 the villus. 



The layer of the muscularis mucosce 

 in the villus forms a kind of thin hollow 

 cone immediately around the central 

 lacteal, and is, therefore, situated be- 

 neath the blood-vessels. It is instru- 

 mental in the propulsion of chyle along 

 the lacteal. 



The lacteal vessels form the com- 



FIG. 383. Vertical section of a villus of 

 the small intestine of a cat. a, 

 FIG. 382. -Vertical section of duode- striated border of the epithelium ; b, 



num. showing a, villi ; b, crypts columnar epithelium ; c, goblet cells ; 



ofLieberkiihn, and c, Brunner's d, central lymph-vessel; e, smooth 



glands in the submucosa s, with muscular fibres ; /, adenoid stroma of 



ducts, d ; muscularis mucosae, m ; the villus in which lymph corpuscles 



and circular muscular coat, /. lie. (Klein.) 



(Schofield.) 



mencement of the intestinal lymphatic system. Each begins almost 

 at the tip of the villus commonly by a dilated extremity. In the 

 larger villi there may be two small lacteal vessels which join, or the 

 lac teals may form a network in the villus (fig. 384). 



Glands. The glands are of two kinds : viz., those of Lieberkiihn 

 and of Brunner. Peyer's patches and the solitary follicles are com- 

 posed of lymphoid nodules. Though sometimes called glands, they 

 form no external secretion. 



The glands or crypts of Lieberkiihn are tubular depressions of the 



