146 HOW WASTES ARE REMOVED FROM THE HOME 



The liquid food soaks through the thin walls of the capil- 

 laries and bathes the cells so that they are continually 

 supplied with food. In the cells the food is oxidized and 

 energy is released. Some of the food containing nitrogen 

 is used to build tissue and repair the body. Nitrogen 

 does not unite easily with oxygen, and hence a consider- 

 able amount of nitrogenous material must be passed from 

 the body as waste. This nitrogenous waste, along with 

 other waste materials, is passed out from the cells into the 

 lymph spaces, then into the lymph tubes, and ultimately 

 gets into the blood again, this time being carried through 

 veins, which are tubes leading toward the heart. Wastes 

 containing nitrogen are finally collected by the kidneys, from 

 which organ they are passed out of the body in the urine. 

 Through the food tube, other wastes and material which 

 cannot be digested are passed out in a partly decayed con- 

 dition from the body. This work of decay is carried on by 

 means of millions of bacteria which live in the lower part of 

 the food tube. 



Why we need a system to remove wastes from the home. 

 All body wastes from the home as well as garbage, used 

 water, and the like must be removed from our homes and 

 put where they cannot do any harm to others. Wastes from 

 the body contain bacteria, possibly some harmful ones. If 

 we were alone in the world we could afford to be selfish, but 

 when we are living where there are many other people, we 

 cannot do anything which might do harm to others. Open 

 privies to which flies can go might be the means of spreading 

 disease among one's own brothers and sisters. Garbage 

 thrown out and left to decay may mean millions of flies 

 for you and your neighbors. Water and wastes from "the 

 kitchen sink allowed to form a dirty, smelling pool outside 



