148 PHYSIOLOGY. 



in the epithelial cell are united with glycerin to make neutral fats 

 to enter the lacteal. Since the soaps are soluble in water, they can 

 enter the portal circulation and be deposited in the liver, but the 

 epithelium of the villus chiefly unites the fatty acid part of the soap 

 to glycerin to form neutral fat, whilst the alkali is excreted into the 

 intestinal canal, to again form more soaps. 



The fats pass between the capillaries beneath the basement 

 membrane of the villus and enter the lacteal, so that chyle has the 

 finest emulsionized fat. About 60 per cent, of the fat ingested is 

 absorbed by the lacteals. Bernard found in the rabbit that the bile- 

 duct opened into the small intestine 30 centimeters above the open- 

 ing of the pancreatic duct, and that the chyle-vessels did not show 

 any fat above the opening of the pancreatic duct. -Dastre bound 

 the bile-duct in a dog and planted the gall-bladder so that it emptied 

 into the middle of the small intestine. Then the pancreatic juice 

 emptied above the entrance of the bile, ^but no chyle was visible 

 until below the entrance of the bile. So that bile plays an impor- 

 tant part in the absorption of fat. 



Bile and pancreatic juice united are the best agency to promote 

 the absorption of fat. 



Harley extirpated the large intestine and attached the lower 

 end of the ileum to the rectum in the dog. The faeces contained 

 five times more water than usual, whilst the fats and carbohydrates 

 were just as those in the normal dog. The absorption of fats and 

 carbohydrates was as usual. The absorption of albumin was reduced 

 to 84 per cent., compared with 95 per cent, in the normal dog. The 

 absorption by the small intestine of salts, carbohydrates, peptones, 

 and fats was originally supposed to be wholly due to osmosis, but 

 now it is held to be a function of the cylindrical epithelium; for the 

 destruction of it by the fluorides permits osmosis alone to be active 

 as in a dead membrane, and the sodium chloride leaves the blood to 

 enter the intestine, whilst with normal epithelium it goes from 

 the intestine into the blood. This function of the epithelium we 

 will, only temporarily, call vital until we can explain it. 



The epithelium of the villus also, during the act of absorption, 

 transforms the peptones into albumin and globulin of the blood, 

 and unites the fatty acids to the glycerin to form the neutral fats 

 of the chyle. 



Hapidity of Absorption. The rapidity of absorption has been 

 determined by experiment. Thus it was found that lithium chloride 

 may be diffused throughout all of the vascular structures and even 



