DIGESTION. 81 



3. The action of pepsin and hydrochloric acid. To 

 part of the above mixture add a few drops 

 of hydrochloric acid and keep it in the water- 

 bath. Compare the two at the end of two 

 or three hours. Have both the proteid and 

 the fat constituents been acted upon ? What 

 shows this? What is the action of gastric 

 juice on milk? 



C. The Pancreatic Juice. 



I. THE PREPARATION OF ARTIFICIAL PANCREATIC 



JUICE. 



Materials. 100 c.c. of water. 15 grains of sodium carbonate, 

 baking soda. 5 grains of pancreatin. ^'<\ 



Apparatus. A small beaker. A water-bath and thermometer. 



The essential elements of pancreatic juice are trypsin, 

 amylopsin, steapsin, and rennin. Trypsin acts upon the 

 proteids, amylopsin upon the carbohydrates, and steapsin 

 upon the fats. The action of rennin is to coagulate what- 

 ever casein may have escaped coagulation by the gastric 

 juice. 



Experiment : 



In the small beaker mix the pancreatin with the aqueous 

 solution of sodium carbonate. Place in the water-bath 

 and keep it at 42 C. 



II. THE ACTION OF PANCREATIC JUICE ON FATS. 

 Pancreatic juice acts upon fats, starch, and proteids. 



Materials. 5 c.c. of olive oil. A tablespoonf ul of flour. 5 c.c. 

 of melted butter. 20 c.c. of artificial pancreatic juice. 



