LESSON XXII. 



THE INTESTINE. 



1. Vertical sections of a cat's or dog's small 

 intestine given out in paraffin (chromic acid *2 p.c. ; 

 stained in bulk with hsematoxylin). Mount in balsam 

 (cp. Less. VI. 4) under the same cover-slip this section 

 and that of 2. 



a. Observe under a low power, the outer longi- 

 tudinal and the inner, thicker, circular muscular coat ; 

 the submucous coat rather thicker than in the stomach 

 (Less. XXI. 1); the mucous membrane consisting of 

 a thin muscularis mucosse, of tubes closed at their 

 ends, the intestinal glands, or glands of Lieberkiihn, 

 with retiform tissue between them ; and of villi, 

 projecting from the upper level of the intestinal glands, 

 they may be either extended and long, or contracted 

 and short, with the surface thrown into folds. 



In the section there may be present one or more 

 lymph follicles. A lymph follicle if present will 

 appear as a round or oval mass, stained conspicuously, 

 by reason of the nuclei of its numerous leucocytes ; its 



