DIGESTION.] PHYSIOLOGY, 1,7 



short time the meat wll gradually disappear. All the 

 proteid matter will be dissolved, and only the wrap- 

 pings of the muscular fibre and the fat be left. You 

 will have a solution of meat — a solution, moreover 

 which, strange to say, will easily pass through mem- 

 branes, and is therefore ready to get into the blood. 



The pancreatic juice and the juice secreted by the 

 intestine act both on starch as saliva does, and on 

 proteids very much as gastric juice does. 



51. The bile and the pancreatic juice together act 

 upon all fats in a very curious way. 



You know that if you shake up oil and water to- 

 gether, though by violent shaking you may mix them 

 a good deal, directly you leave off they separate 

 again, and all the oil is seen floating on the top of 

 the water. If, however, you shake up oil with pan- 

 creatic juice and bile, the oil does not separate. You 

 get a sort of creamy mixture, and will have to wait 

 a very long time before the oil floats to the top. 

 Milk, you know, contains fat, the fat which is gene- 

 rally called butter. If you examine milk under the 

 microscope, you will find that the fat is all separated 

 into the tiniest possible drops. So also, when you 

 shake up oil or butter, or any other fat, with bile 

 and pancreatic juice, you will find on examination 

 that the fat or oil is all separated into the tiniest 

 possible drops. What is the purpose of this ? 



If you look at the inside of the small intestine 

 of any animal, you will find that it is not smooth and 

 shiny like the outside of the intestine, but shaggy, 

 or, rather, velvety. This is because the mucous 

 membrane is crowded all over with little tags, like 

 very little tongues, hanging down into the inside of 



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