I IO 



Life and Health 



Into this portion opens the bile duct from the liver and the 

 duct from the pancreas, which first unite and then enter 

 the intestine as a common duct. 



The next portion of the intestine 

 is called the jejunum, because it is 

 usually empty after death. 



The remaining portion, known 

 as the ileum, terminates in the 

 right iliac region, and opens into 

 the large intestine. This opening 

 is guarded by the ileo-caecal valve, a 

 kind of movable partition provided 

 with a button-hole slit. This valve 

 permits the passage of material from 

 the small to the large intestine, but 

 prevents its backward movement. 



Experiment 45. To show that pepsin 

 and acid are necessary for gastric diges- 

 tion. Take three beakers, or large test 

 tubes ; label them A, B, C. Put into A 

 water and a few grains of powdered 

 pepsin. Fill B two-thirds full of dilute 

 hydrochloric acid (one teaspoonful to a 

 pint), and fill C two-thirds full of dilute 

 hydrochloric acid and a few grains of 

 pepsin. Put into each a small quantity 

 of well-washed fibrin, and place them all 

 in a water bath at 104 Fahr. for half 

 an hour, or in any other warm place. 



Examine them. In A, the fibrin is 

 unchanged ; in B, the fibrin is clear and 

 swollen up ; in C, it has disappeared, 

 having first become swollen and clear, 

 being finally converted into peptones. 



FIG. 54. 



(A highly magnified view of a 

 peptic or gastric gland, which 

 is represented as giving off 

 branches. It shows the co- 

 lumnar epithelium of the sur- 

 face dipping down into the 

 duct D of the gland, from 

 which two tubes branch off. 

 Each tube is lined with co- 

 lumnar epithelial cells, and 

 there is a minute central pas- 

 sage with the " neck " at N. 

 Here and there are seen other 

 special cells, called parietal 

 cells, P, which are supposed 

 to produce the acid of the 

 gastric juice. The principal 

 cells are represented at C.) 



and completely dissolved, 



Therefore, both acid and ferment are required for gastric digestion. 



