ABSORPTION. 



163 



Fig. 39. 



tissue. The glandulse agminatae (Fig. 38), or " Fever's patches," as 

 they are sometimes called, consist of aggregations of similar globular 

 or ovoid bodies, found most abundantly toward the lower extremity 

 of the small intestine. Both the solitary and agminated glandules 

 are evidently connected with the lacteals and the system of the 

 mesenteric glands, which latter organs they resemble very much in 

 their minute structure. They are probably to be regarded as the 

 first row of mesenteric glands, situated in the walls of the intestinal 

 canal. 



Another set of organs, intimately connected with the process of 

 absorption, are the villi of the small intestine. These are conical 

 vascular eminences of the mucous membrane, thickly set over the 

 whole internal surface of the small intestine. In thejipper.partiQji,of 

 the intestine, they are flattened and triangular in form, resembling 

 somewhat the conical projections of the pyloric portion of the sto- 

 mach. In the lower part they are long and filiform, and often 

 slightly enlarged, or club-shaped at their free extremity (Fig. 39), 

 and frequently attaining the length of 

 one thirty-fifth of an inch. They are 

 covered externally with a layer of 

 columnar epithelium, similar to that 

 which lines the rest of the intestinal 

 mucous membrane, and contain in their 

 interior two sets of vessels. The most 

 superficial of these are the capillary 

 bloodvessels, which are supplied in each 

 villus by a twig of the mesenteric 

 artery, and which form, by their fre- 

 quent inosculation, an exceedingly close 

 and abundant network, almost imme- 

 diately beneath the epithelial layer. 

 They unite at the base of the villus, 

 and form a minute vein, which is one 

 of the commencing rootlets of the por- 

 tal vein. In the central part of the vil- 

 lus, and lying nearly in its axis, there 

 is another vessel, with thinner and more 



transparent walls, which is the commencement of a lacteal. The 

 precise manner in which the lacteal originates in the extremity of 

 the villus is not known. It commences near the apex, either by a 

 blind extremity, or by an irregular plexus, passes, in a straight or 



EXTREMITY OF I > r E s T i > A i, 

 VILLCS, from the Doir. . Layer of 

 epithelium. 6. Bloodvessel, c Lacteal 

 vessel. 



