INTESTINES. 



107 



The Peritoneal coat is the external, being included in the lower 

 edge of the mesentery. 



The Muscular coat is thin, and consists of pale fibres ; the super- 

 ficial and longitudinal* are not 



Fig. 87. 



and longitudinal 

 distinct ; the remainder are cir- 

 cular^ *. 



The Cellular coat connects the 

 muscular and mucous, and con- 

 tains the vessels and nerves ; 

 when inflated with air and dried, 

 it appears like cotton, as is the 

 case in the stomach. 



The Mifcous coat is longer 

 than any other, and hence must be thrown into numerous folds, 

 which are called valvulce conniventes ; these are circular and over- 

 lapping, and more numerous" and larger^ in the upper portion of the 

 intestine, than in the lower. The surface of the mucous membrane 

 is covered with a number of papillary projections called villi^ many 

 of which are conical in shape. Each villus consists of an artery, vein, 

 and lacteal. This lacteal does not open directly upon the surface of 

 the mucous membrane, but the chyle is conveyed into the intestine 

 by the intervention of cells. 



Fig. 89. 



Brunnefs Glands are a number of small solitary glands, which 

 are with difficulty perceived by the naked eye. They are most abun- 

 dant near the duodenum^ but exist in a scattered manner throughout 

 the intestine. 



Peyer'^s Glands are larger, and exist principally in the lower part 

 of the small intestine. They are fiat and elliptical, and vary in size, 



