172 ANATOMY FOR, NUESES. [CHAP. XV. 



formed, by the blood-vessels in the walls of the stomach, 

 though some pass in the chyme through the pylorus into the 

 small intestine. 



Changes the food undergoes in the small intestine. The chyme 

 on entering the duodenum, after an ordinary meal, is a mixture 

 of various matters. It contains some undigested proteids ; some 

 undigested starch ; oils from fats eaten ; peptones formed in the 

 stomach, but not yet absorbed ; salines and sugar which have 

 also escaped complete absorption in the stomach ; all mixed with 

 a good deal of water and the secretions of the alimentary canal. 

 This acid mixture passing into the duodenum excites the secre- 

 tory action of the pancreas, and stimulates the bile to flow from 

 the gall-bladder; the glands of Lieberkiihn and Brunner also 

 become active, and all these secretions being alkaline, the acid 

 chyme is rapidly changed into an alkaline preparation, called 

 chyle. 



Bile. Bile, secreted in the lobules of the liver and stored in 

 the gall-bladder until needed, is a fluid of a bright golden red 

 colour, with an alkaline reaction. The chief solid constituents 

 of bile are the bile-salts and the colouring-matters or pigments. 



Action of bile on food. Upon proteids and starch, bile has 

 little or no digestive action. On fats, it has a slight solvent 

 action, and, in conjunction with pancreatic juice, has the power 

 to emulsify them. Bile possesses some antiseptic qualities. 

 Outside the body, its presence hinders putrefactive changes; 

 and when it is prevented from flowing into the alimentary 

 canal, the contents of the intestine undergo changes which do 

 not otherwise take place, and which lead to the appearance of 

 various products, especially of ill-smelling gases. Lastly, the 

 passage of fats through membranes is assisted by wetting the 

 membranes with bile or with a solution of bile-salts. It is 

 known that oil will pass to a certain extent through a filter- 

 paper, kept wet with a solution of bile-salts, whereas it will 

 not pass, or passes with extreme difficulty, through one kept 

 wet with distilled water. 



Pancreatic juice. Healthy pancreatic juice is a clear, some- 

 what viscid fluid, with a very decided alkaline reaction. It is 

 actively secreted by the pancreas during digestion and flows 

 into the intestine in conjunction with the bile. The Germans 

 call the pancreas the " abdominal salivary gland," though the 



