SUMMARY 457 



children. Tobacco is positively harmful to immature 

 persons, and alcohol as a beverage or common stimulant 

 must be classed as a poison. Proper cooking renders most 

 food both more palatable and more digestible. 



Microscopic dependent plants cause changes in food. The 

 yeast plant is employed in bread making ; certain bacteria 

 change cider to vinegar; and others are responsible for the 

 fine flavors of the best butter, cheeses, and certain kinds 

 of meat. Still other bacteria cause foods to spoil. To 

 preserve food against such bacteria, we dry it, freeze it, 

 smoke it, boil it, and seal it in air-tight receptacles ; or employ 

 sugar, salt, spices, or vinegar as preservatives. 



Some bacteria enter the body and cause diseases. This 

 explains why we disinfect wounds, quarantine persons suf- 

 fering from infectious diseases, and cleanse thoroughly or 

 destroy all household articles with which such people come 

 in contact. The body fights disease germs by means of the 

 white corpuscles of the blood and by means of antitoxin 

 secreted by the cells of the body. Every household should be 

 supplied with certain common disinfectants; and every 

 household and community should guard against infected 

 food and water, and attend to the proper disposal of waste 

 and sewage. One of the most effective means of combating 

 or preventing disease is to maintain cleanliness. 



Flies are great carriers of disease bacteria, and certain 

 kinds of mosquitoes, fleas, and other insects cause diseases 

 by injecting disease-producing protozoa into the blood of 

 victims. 



Exercise, bathing, nutritious food, proper clothing, fresh 

 air, sunshine, sufficient rest and sleep, avoidance of harmful 

 stimulants and drugs, shunning of cure-all patent medicines, 

 and cheerfulness are among the essentials to health. 



