n8 



ELEMENTS OF MAMMALIAN ANATOMY. 



verse extends crosswise, connecting the ascending with the 

 descending, which lies on the left side. The descending- 

 colon terminates in the rectum, which 

 is five or six centimeters long. 



The wall of the alimentary canal 

 is composed of three chief coats mu- 

 cous, areolar, and muscular. These 

 coats may be seen by cutting trans- 

 versely, with a sharp scalpel, a portion 

 of the stomach hardened in formalin. 

 The mucous coat (Fig. 62) lines the 

 lumen and contains the numerous 

 glands which vary much in the differ- 

 ent portions of the canal. The esoph- 

 agus contains the esophageal glands, 

 whose secretion probably has no other 

 effect on the food than to facilitate its 

 passage. The mucous coat of the 

 stomach contains the gastric glands, 

 which yield pepsin and hydrochloric 

 acid, the chief agents of the gastric 

 digestive fluid (Fig. 63). The glands 

 in the cardiac end of the stomach differ 

 from those in the pyloric end in con- 

 taining numerous parietal or acid cells 

 which probably secrete the hydro- 

 chloric acid for digestion. 



The mucous coat of the small intes- 

 tine contains tube-like glands, the 

 glands of Lieberkiihn, whose secretion 

 In the duodenum and jejunum the mu- 

 cous membrane is thrown into numerous transverse folds, 

 valvuli conniventes, which increase the surface for absorp- 

 tion. The villi are minute finger-like processes (Fig. 64), 



FIG. 63. A CROSS - 



SECTION OF THE MU- 

 COUS COAT OF THE 

 STOMACH BETWEEN 

 THE LINES a AND c 

 IN FIG. 60 SHOWS 

 A GASTRIC GLAND. 

 X 250. Diagram- 

 matic. 



a, Mouth of gastric 

 gland ; e, columnar 

 epithelial cells on 

 the food surface of 

 the stomach ; /, lu- 

 men of a gland; o, 

 oxyntic or acid cell. 



acts on the sugars. 



