PHENOMENA OF INTESTINAL DIGESTION. 



159 



Fig. 35. 



cles also begin to become altered in the duodenum. The solid 

 granular fat of beef, and similar kinds of meat, becomes liquefied 

 and emulsioned ; and appears 

 under the form of free oil 

 drops and fatty molecules; 

 while the fat vesicle itself is 

 partially emptied, and becomes 

 more or less collapsed and 

 shrivelled. In the middle 

 and lower parts of the intes- 

 tine (Figs. 35 and 86) these 

 changes continue. The mus- 

 cular fibres become constantly 

 more and more disintegrated, 

 and a large quantity of granu- 

 lar debris is produced, which 

 is at last also dissolved. The 



, -IT FROM MIDDLE OP SMALL INTESTINE a, a. 



tat also progressively dlSap- Fat vesicles, nearly emptied of their contents. 



Fig. 36. 



pears, and the vesicles may 

 be seen in the lower part of 

 the intestine, entirely collapsed 

 and empty. 



In this way the digestion of 

 the different ingredients of 

 the food goes on in a continu- 

 ous manner, from the stomach 

 throughout the entire length 

 of the small intestine. At the 

 same time, it results in the 

 production of three different 

 substances, viz : 1st. Albumi- 

 nose, produced by the action 

 of the gastric juice on the 

 albuminoid matters ; 2d. An 

 oily emulsion, produced by the action of the pancreatic juice on 

 fat ; and, 3d. Sugar, produced from the transformation of starch 

 by the mixed intestinal fluids. These substances are then ready 

 to be taken up into the circulation ; and as the mingled ingredients 

 of the intestinal contents pass successively downward, through the 

 duodenum, jejunum, and ileum, the products of digestion, together 

 with the digestive secretions themselves, are gradually absorbed, 



FROM LAST QUARTER OF SMALL IXTESTIITE. 



a, a. Fat vesicles, quite empty and shrivelled. 



