SUMMARY 421 



fills the larger part of the abdomen. The inner wall of 

 the tube is lined with glands which secrete digestive juices, 

 and into the intestine are poured the secretions from two 

 large glands, the pancreas and the liver. The small intes- 

 tine is the great digestive organ of the body. Here the fats 

 and oils are digested, and the digestion of the starches and 

 proteins is completed. The small intestine opens through a 

 valve into the large intestine, a tube five or six feet long 

 decreasing in size toward the exit from the body. There 

 is little digestion in the large intestine. 



The changes that take place in the food as it passes 

 through the alimentary canal are very complex, but dur- 

 ing its progress the valuable part of the food is so changed 

 and prepared that it can be absorbed by the blood and 

 transported by it to the different parts of the body where 

 its energy is needed. Absorption takes place all along 

 the alimentary canal wherever the food has been suffi- 

 ciently prepared. 



In the entire process of digestion of food the only part 

 that can be controlled by the individual is the chewing of 

 the food. It is necessary that the food be ground fine in 

 order that the digestive juices may readily act upon it and 

 not leave any undigested fragments as abiding places for 

 germs. Decayed and unbrushed teeth furnish unlimited 

 breeding places for germs. Careful experiments have shown 

 that the health of the body and the mental vigor are greatly 

 increased by properly caring for the teeth. The teeth must 

 be kept clean and all cavities must be properly filled if health 

 is to be maintained. 



SUMMARY 



Plants and animals make up the live part of the earth. 

 Most green plants consist of root, stem, and leaves. The root 



