MANUAL OF HISTOLOGY. 



THE SMALL INTESTINE. 



The serous coat presents no structural characteristics pecu- 

 liar to itself, closely resembling the gastric peritoneum. It 

 encloses a muscular coat and the mucous membrane, which are 

 held together by connective tissue. The average thickness 

 of these layers does not, in man, exceed 1.0 mm., of which 

 three-fourths belong to the muscular, and one-fourth to the 



Fio. 168. Longitudinal section of the small intestine of a rabbit : Z, Z, yilli ; J, crypts; Pp, a Peyer's 

 patch ; K, cap of a follicle ; S, subnmoosa ; m. m, muscularis mucosae ; R, circular muscular layer ; L, 

 longitudinal muscular layer ; P, peritoneum. Veraon. 



mucous coat. Of course, the contracted or relaxed condition 

 of the intestinal tube at the time of measurement will appre- 

 ciably influence these figures. But they represent the general 

 ordinary average. 



The muscular coat has an external longitudinal and an in- 

 ternal circular layer. Between the two we find Auerbach's 



