1 76 Physiology. 



3. The bile, to a certain extent, is waste matter ; so the 

 liver is an organ of excretion as well as an organ of secretion. 



4. It is found that if, for any cause, the bile is prevented 

 from entering the intestine, .constipation follows, and the 

 contents of the large intestine have a much more fetid 

 odor than usual. The bile retards this putrefaction. 



The Pancreas. Just back of the stomach is another im- 

 portant gland, the pancreas. It is a pink organ, weighing 

 three or four ounces and having the shape of a dog's 

 tongue. It has a duct which empties into the small intes- 

 tine at the same point where the bile enters, but it has no 

 sac in which to store the liquid which it secretes. It takes 

 from the blood certain materials and makes a liquid called 

 pancreatic juice. 



Pancreatic Juice. This is a clear, sticky liquid, very 

 much like saliva in appearance. Although the pancreas is 

 a small organ, its work is very important. It gets a large 

 blood supply and makes a large amount of pancreatic juice. 

 The pancreas is often eaten, being known by the name 

 " sweetbread." 



The Work of the Pancreatic Juice. The pancreatic juice 

 acts on all the principal classes of foodstuffs : 



1. A substance in it called am^lopsin acts on starches, 

 changing them to sugar even more actively than the ptyalin_ 

 of the saliva. 



2. Another substance in pancreatic juice is trypsin ; like 

 the pepsin of gastric juice, it changes proteids to peptones. 



3. The pancreatic juice also emulsifies the fats. The 

 fat is divided into exceedingly fine drops, each covered 

 with a coating of albumen. An emulsion can be made 

 artificially by shaking together water, oil, and white-of-egg, 



