5f PLAIN FACTS FOE OLD AND YOUNG 



small intestine widens out into the colon, or large in- 

 testine, which is about five feet in length, and completes 

 the digestive apparatus. 



Five Wonderful Fluids.— As we have already 

 noted, there are several fluids concerned in the process 

 of digestion, —the saliva, the gastric juice, the bile, the 

 pancreatic juice, and the intestinal juice. These are 

 all used to dissolve the food so it can be absorbed by, 

 or taken into, the blood. Each fluid has its particular 

 work to do in transforming some portion of the food 

 into a substance different from what it was, and pre- 

 paring it to be received into the blood and converted 

 into tissue. Thus, the saliva acts upon the starch of 

 the food, changing it to sugar. The gastric juice di- 

 gests albumen. The bile digests fat, and aids in the 

 absorption of other portions of food after being di- 

 gested. The pancreatic juice digests starch, albumen, 

 and fats, the three most important elements of food. 

 The intestinal juice digests each of the kinds of food 

 elements mentioned above, and also cane sugar. It is 

 important to notice that cane sugar is digested only by 

 the intestinal juice, which acts, not throughout the 

 whole alimentary canal, but only in the intestinal por- 

 tion of it. 



Digestion of a Mouthful of Bread. —If we could 

 see a morsel of bread undergoing digestion we should 

 notice, first, that while it is being chewed, the saliva 

 converts a small portion of the starch into sugar. 

 After it is swallowed, the gastric juice begins its work, 

 and digests the albuminous portion of the bread, known 

 as gluten. Just after it passes out of the stomach into 

 the intestine, the liver and gall bladder contract, and 

 pour out a quantity of bile, which searches out any 

 little jDortion of oil the bread may contain, or the but- 



