194 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



network of blood- and lymph- vessels. The physio- 

 logical action of this muscle causes adjacent leaves 

 to rub against each other, producing a trituration of 

 the retained food. The muscular coat is fasciculated 

 and thin and composed of two layers that pass in dif- 

 ferent directions. The serosa presents nothing differ- 

 ent from the general structure of the peritoneal lining. 



SMALL INTESTINE, 



The small intestine is about twenty-four feet long, 

 and is divided into duodenum, ten inches : jejunum and 



_ Villus. 



- Crypt of Lieberkiihn. 

 Muscularis mucosa. 



r - Circular muscle layer. 



Longitudinal muscle 



layer. 

 Serous coat. 



Fig. 142. Cross-section of small intestine. 



ileum, respectively, two-fifths and three-fifths of the 

 remainder. About three feet from the lower end of 



