THE INTESTINES. 



403 



magnificent network of peripheral capillary blood-vessels ; the whole being 

 inclosed in a complete epithelial sheath. 



A. VILLI 



OF MAN, SHOWING THE BLOOD-VESSELS AND LACTEALS. B. VILLUS 

 OF A SHEEP, 



The orifices opening on the intestinal mucous membrane belong either to 

 Brunner's (duodenal) glands, or to those of Lieberkuhn (simple follicles). 



Brunner's glands form a continuous 

 layer beneath the duodenal mucous mem- 

 brane. In their organisation, these small 

 granular bodies are exactly like the acini 

 of the salivary glands ; each acinus pos- 

 sesses an extremely short excretory duct, 

 that passes through the mucous mem- 

 brane. (These racemose glands secrete 

 a clear alkaline mucus, which contains 

 no formed elements, such as cells or 

 nuclei.) 



The glands (or cryptse mucosse) of 

 Lieberkuhn or Galeati are placed in the 

 substance of the mucous membrane, and 

 are distinguished by their microscopical 

 dimensions, their considerable number, 

 and their tubular form, which has caused 

 each of them to be compared to the finger 

 of a glove; they are implanted perpen- PORTION OF ONE OF BB^NER'S GLANDS. 



