7 8 



Physiology. 



Gullet 



Stomach 

 Duodenum 



Review of the Digestive Tube. The whole digestive 

 tube may be briefly and roughly described as a muscular 



tube of varying diameter, 

 lined by mucous mem- 

 brane. The muscular coat 

 pushes the contents along 

 and mixes them with liq- 

 uids ; the mucous coat is 

 beset with glands, making 

 liquids, some of which 

 merely soak the food, 

 others act on it chemically, 

 | while mucus serves to 

 | make the surface slippery, 

 o It seems that these myriads 

 of simple glands are not 

 enough, so several large 

 compound glands lie along- 

 side the food tube and 

 empty their secretions into 

 it by ducts; these com- 

 pound glands are the sali- 

 vary glands, the pancreas, 



Fig. 76. The Stomach and Intestines. an d the liver. 



Length of the Intestine. The length of the small in- 

 testine is about twenty-five feet, and of the large intestine 

 five or six feet. The large intestine is not a direct contin- 

 uation of the small ; that is, the small intestine opens at a 

 right angle into the large near the beginning of the latter, 

 so that there is a short blind end called the cecum (see 

 Fig. 76). In some animals this is large and has consider- 

 able length, but in man it is very short. There is a closed 



Vermiform 

 Appendix 



Rectum 



