CHAPTER V 

 PRESERVATIVES AND DISINFECTANTS 



24. Germs. The world is full of many kinds of 

 microscopic living organisms. They are one-celled bodies. 

 Some are animals and some are plants. The one-celled 



plants are known as bacteria. 

 Most of the bacteria are very 

 valuable and serviceable to 



man. Some of these are in 

 BACTERIA OF VARIOUS KINDS , . 



the soil and prepare food for 



Magnified 1000 diameters. 



the trees and vegetables and 



grains upon which man is dependent for food. Others 

 are useful in souring milk, ripening cheese, and making 

 cider vinegar. Others decompose dead matter, such as 

 fallen trees, grass, and dead animals, and thus prevent 

 them from collecting in quantity on the earth. 



But when these act on things which man wants to 

 keep, then they are considered harmful. They will 

 decompose railroad ties, 

 telephone poles, all kinds 

 of wood fixtures, meats, 

 and other foods. Mold is 

 also very destructive. It 

 will destroy bread, damp 

 clothing, fruits, etc. The 

 yeast plant is also respon- 

 sible for the souring of 



MOLD PLANTS 

 (Magnified.) 



