DIGESTION 135 



side of the liver. This fluid is of a greenish-yellow color, hav- 

 ing a peculiar smell, and a very bitter taste ; its exact part in 

 the process of digestion is not known. That it is an impor- 

 tant one, cannot be doubted. For if its proper flow into the 

 intestinal canal is interfered with, or stopped, serious illness 

 is the result. Its chief function seems to be to aid in the 

 digestion of fats, by emulsifying them ; it also acts as a disin- 

 fectant of the intestinal tract, increases the muscular contrac- 

 tions of the intestines, and aids in a general way, in the 

 absorption of the products of digestion. (Read Note 7.) 



37. The pancreatic juice is the product of a gland called the 

 pancreas, situated behind the stomach. This fluid is colorless, 

 watery, alkaline, and without odor. Like the digestive juices 

 previously described, it owes its solvent power to its peculiar 

 ferments. The most important of these ferments, called pan- 

 creatin, transforms starch into sugar. Another, trypsin, causes 

 the solution of uudissolved albuminoid substances ; and a third 

 ferment, which has not received a name, causes a partial acidi- 

 fication of the fats. By the joint action of these fluids, the 

 food is prepared for absorption. There results from this action 

 of the pancreatic juice a white and milky fluid, termed the 

 chyle, which holds in solution the digestible portions of the 

 food, and is spread over the extensive absorbent surface of 

 the small intestines.' (Read Note 8.) 



38. The mucous membrane of the intestines, also, secretes 



7. Experiment. Bile. The chief function of the bile in the diges- 

 tion of food is the emulsifying of fats. 



If a quantity of oil is shaken up with an 'equal part of water in a test- 

 tube, the two will not mix. But if we substitute bile for the water, and 

 shake thoroughly, we obtain an emulsion which will separate but slowly 

 and imperfectly. 



The bile may be obtained from the gall-bladder of the ox or sheep at 

 any butcher's or slaughter-house. 



37. What produces the pancreatic juice ? 

 Where is the pancreas situated ? 

 Describe pancreatin. Trypsin. 

 How is food prepared for absorption f 

 What is chyle ? What is its function ? 

 How performed ? 



