168 THE HUMAN BODY. 



pancreatic secretion, are partly taken up by its lymphatics 

 and partly by its blood-vessels. The emulsified fats main- 

 ly pass into the lymphatics of the villi, and are carried off 

 by them. 



The Lacteals. The innumerable tiny fat drops drained 

 off by the intestinal lymphatics or lacteals after an 

 ordinary meal make their contents look white and milky, 

 hence the name.* During fasting the lymphatics of the 

 small intestine, like those in other parts of the body (see 

 Chap. XIII.) convey a clear colorless liquid. 



Absorption from the Large Intestine. In the duo- 

 denum the bulk of food entering from the stomach is 

 increased by the bile and pancreatic secretions poured out 

 on it. Thenceforth absorption overbalances excretion, and 

 the food-mass becomes less and less in bulk to the lower 

 end of the ileum. The contractions of the small intestine 

 drive on its continually diminishing contents, until they 

 reach the ileo-colic valve, through which they are ulti- 

 mately pressed. When the mass enters the large intestine 

 its nutritive portions have been almost entirely absorbed, 

 and it consists chiefly of some water, with the indigestible 

 portions of the food and of the secretions of the alimentary 

 canal. It contains cellulose, elastic tissue, mucin, and 

 somewhat altered bile pigments; commonly some fat if a 

 large quantity has been eaten; and some starch, if raw veg- 



How are emulsified fats carried off? 



What are the lacteals? Why so called? Under what conditions 

 do the lacteals not contain milky looking chyle? 



In what part of the alimentary canal does absorption more than 

 balance the amount of liquid poured out on the food? 



What are the constituents of the mass passing from the small into 

 the large intestine? What changes does this mass undergo as it 

 passes along the large intestine? 



* From Latin, lac, milk. 



