FUNCTIONS OF PANCREATIC JUICE. 219 



ingly fine drops, each enveloped in a coating of albuminous 

 substance. Milk is a natural emulsion. Examine a drop of 

 milk under the microscope. An emulsion can be made artifi- 

 cially by shaking together water, oil, and white of egg. The 

 shaking breaks the oil into fine drops, which would soon gather 

 again if no other substance were present ; but it is supposed 

 that the albumen forms a thin coating around each droplet, 

 enabling it to remain distinct in the liquid. 



(b) The fats are also acted on chemically by Steapsin, an- 

 other ferment of the pancreatic juice ; they are decomposed 

 with the formation of free fatty acids, and thus more fully 

 prepared to be absorbed and to' build up the tissues. These 

 free fatty acids aid in the work of emulsifying the rest of the 

 fat. 



Saliva acts only on starch ; gastric juice, on proteids ; bile, 

 on fats ; whereas pancreatic juice acts on all three, and prob- 

 ably more energetically than the above-named liquids. 



The intestinal juice contains a ferment called Invertin, 

 which changes cane sugar to dextrose, which is a variety of 

 grape sugar. Dextrose is less soluble than cane sugar. Here, 

 then, is an exceptional case, in which a digestive process con- 

 verts a more solu- 

 ble substance into a 

 less soluble form. Vi ,,j- 



The bile and the 

 pancreatic juice are openings of 

 alkaline, and over- Glands 



COme the acidity Of Intestinal Glands 



the chyme. 



Absorption. Flg - 64 - Mucou s Membrane of Small Intestine, 



The mucous mem- 

 brane of the small intestine is thrown into ridges ; but, unlike 

 those of the stomach, they run transversely. 



