3 1 2 DIGESTION. 



that which the small labial and buccal glands occupy in 

 relation to the larger salivary glands, the parotid and 

 subm axillary. 



The Villi (figs. 80, 81) are confined exclusively to the 

 mucous membrane of the small intestine. They are minute 

 vascular processes, from a quarter of a line to a line and two- 

 thirds in length, covering the surface of the mucous mem- 

 brane, and giving it a peculiar velvety, fleecy appearance. 

 Fig. 79.* 



Krauss estimates them at h'fty to ninety in number in a 

 square line, at the upper part of the small intestine, and at 

 forty to seventy in the same area at the lower part. They 

 vary in form even in the same animal, and diifer according 

 as the lymphatic vessels they contain are empty or full of 

 chyle ; being usually, in the former case, flat and pointed 

 at their summits, in the latter cylindrical or clavate. 



Each villus consists of a small projection of mucous 

 membrane, and is composed from without inwards of the 

 following parts : Epithelium, basement membrane, blood- 



* Fig. 79. Enlarged view of one of Brunn's glands from the human 

 duodenum (from Frey). The main duct is seen superiorly ; its branches 

 are elsewhere hidden by the bunches of opaque glandular vesicles. 



