120 SUMMARY CONCERNING DIGESTION. 



end the indigestible residue collects, ready to be expelled 

 from the body. 



16. Summary. When digestion and absorption are 

 completed, all the useful portions of a meal have at last 

 been mixed with the blood. Some of them, as water, 

 were ready for absorption without undergoing any 

 change; all we had to do was to swallow them, and the 

 coats of the stomach took them up at once, if there was 

 not too much of them. Others, as a pinch of salt or a 

 lump of sugar, were ready to dissolve at once. Still 

 others, like the lean of meat, and starchy foods, had to 

 be changed by the digestive liquids before they could 

 be dissolved. 



Some were changed by saliva, some by the gastric 

 juice, others by the liquids of the intestines; but sooner 

 or later, in mouth or stomach or bowels, they were made 

 ready for absorption. 



Some of the nutritive liquid was absorbed by the 

 blood-vessels of the stomach; more by the blood-vessels 

 of the intestinal villi; still more by the lacteals. What 

 little may still have been left, was sucked up into the 

 blood- and lymph- vessels of the large intestine. But no 

 matter where it was absorbed, or by what vessels, it 

 finally reaches the blood, and supplies it with water and 

 minerals and albumens and fats and sugar, to be carried 

 to every organ. 



16. What has happened when the digestion and absorption of a 

 meal are completed? Name a food-stuff absorbed without change. 

 One which has to be simply dissolved. Some which had to be changed 

 by the digestive juices before they could be absorbed. Name the 

 liquids used in changing them. Name the vessels concerned in the 

 absorption. With what does the absorbed liquid supply the blood ? 



