FUNCTIONS OF THE INTESTINES. 



321 



Jt is very evident, therefore, that we have, in each follicle, a 

 powerful adjunct to the overlying villi, to add still another 

 prophylactic means to those already enumerated. While the 

 villi do not occur upon the portion of the follicle that projects 

 into the intestinal free surface, they are nevertheless present 

 around it, and their lacteals when below the level of the epithe- 

 lium break up into vessels which find their way to the lymph- 

 sinus. "When they reach the level of the closed follicles," says 

 Berdal, 9 "the chyliferous vessels become united to the sinuses 

 of these follicles, of which they constitute the afferent vessels. 

 Crossing the muscularis mucosae, they form part of a varicose 

 capillary net-work in the submucosa. From this net-work 

 arise true lymphatic trunks supplied with valves that cross the 

 intestinal coats and then reach the subperitoneal lymphatic 

 net-work." 



The intimate relationship between the villus and the lym- 

 phatic follicle is further emphasized by the similarity which 

 their mechanisms present. If the lymph-sinus of the latter is 

 considered as functionally encircling what in the villus has 

 been termed cytogenous tissue by Kolliker, including its net- 

 work of capillaries, this similarity becomes striking. Indeed, 

 the fact that the sinus is situated around the lymphoid tis- 

 sue instead of in its center, as it is in the villus, would tend 

 to indicate that the follicle does not absorb intestinal fluids, 

 since these would merely, before reaching the sinus, be sub- 

 jected to what epuration the epithelium and the fenestrated 

 membrane overlying the organ could afford. It is, therefore, 

 probable that the solitary follicle or organ does not include 

 absorption among its attributes. Indeed, unless possessed of 

 a suction mechanism such as that of the villi, it is evident that, 

 surrounded, as is its projecting part, by these minute pumps, 

 its usefulness would be very slight. 



What can be the use, therefore, of the minute apertures 

 encircling the projecting part of the follicle and which con- 

 stitute the "fenestrated" subepithelial membrane? "These 

 orifices appear," says Berdal, "to afford passage to lymphatic 

 cells that emigrate from the follicle toward the cavity of the 



Berdal: "Histologie Normals," p. 365, 1894. 



