THE CASTRO-INTESTINAL CANAL. 149 



than in the stomach, and is richly infiltrated with 

 small spheroidal and variously shaped cells. In it 

 lie imbedded tubular glands, not unlike the mucous 

 glands of the stomach, but not crowded so closely 

 together. These glands are often called the folli- 

 cles of Lieberkiihn, and are lined with cylindrical 

 epithelium. Rising from the general surface of the 

 mucous membrane, between the orifices of the 

 glands, are very numerous short cylindrical or coni- 

 cal projections called villi. These are formed by 

 projections inward of the mucosa ; they are covered 

 by cylindrical epithelium, and contain an abundant 

 vascular net-work, and the radicles of the lymph- or 

 chyle-vessels. 



The cylindrical epithelial cells are joined to- 

 gether, side by side, by cement substance, and pos- 

 sess a marked peculiarity in the structure of the 

 free border, which is considerably thickened, and is 

 crossed, in a direction corresponding with the long 

 axis of the cell, by fine parallel, closely-set lines, 

 which are usually interpreted as tiny pores or canals 

 passing through the border. It was formerly taught 

 that through these pores the chyle passed to enter 

 the epithelium on its way to the lymph-vessels. 

 More recently, however, the view has been ad- 

 vanced that substances absorbed into the lymph- 

 vessels from the intestines pass, not through the 

 epithelial cells, but through the cement substance 

 between them. 



