ABSORPTION AND ASSIMILATION OF FOODSTUFFS 145 



shown by the milky contents of the lacteals. Hence it is 

 difficult to decide in how far the splitting up and emulsifica- 

 tion of fats take place. 



The absorption of emulsified fat is supposed to be brought 

 about by the active movements of the striated border of the 

 epithelial cells. 



The absorption of fats is aided by the bile. Animals with 

 a biliary fistula absorb but little of the fat eaten. This favor- 

 able action of bile' is supposed to be due to the fact that it 

 dissolves free fatty acids and the insoluble calcium and mag- 

 nesium soaps, and that the striated border of the epithelial 

 cells is, by the bile, rendered permeable for the emulsified 

 fat. Both these actions are attributed to the bile salts. 

 The soda of the bile also aids in the emulsification of fats. 



If, by pancreatic extirpation, the steaptic digestion is pre- 

 vented, the amount of fat absorbed is greatly reduced. 

 This, however, is not true for the fat of milk, for this is 

 already in a finely emulsified condition. 



From the epithelial cells the emulsified fat is transferred 

 to the lymph and with this is carried through the thoracic 

 duct into the blood. The fat, in so far as it is not directly 

 oxidized, is stored up in the cells of the adipose tissues of 

 the body. 



The amount of fat in the blood is somewhat greater during 

 fat absorption than during fasting. During starvation the 

 amount of fat in the blood is also increased, for then the fat 

 stored up in the tissues is transported by the blood to the 

 place of combustion. 



Immediately after a meal rich in fat, large quantities of 

 fat appear in the liver cells (physiological filtration of fat), 

 which disappear after a short time. 



4. ABSORPTION AND ASSIMILATION OF CARBO- 

 HYDRATES 



The monosaccharides are carried by the portal vein to the 

 liver without having undergone any change in the walls of 

 the intestine. 



