PLANTS WITHOUT CHLOROPHYLL 



149 



Of these, the last named is the most powerful as well as the most 

 dangerous to use. As it attacks metal, it should not be used in a 

 metal pail or dish. It is commonly put up in tablets which are 

 mixed to form a 1 to 1000 solution. Such tablets should be care- 

 fully safeguarded because of possible accidental poisoning. 



Formaldehyde used in liquid form is an excellent disinfectant. 

 When burned in a formalin candle, it sets free an intensely 

 pungent gas which is often used for disinfecting sick rooms after 

 the patient has been removed. 



Carbolic acid is perhaps the best disinfectant of all. If used 

 in a solution of about 1 part to 25 of water, it will not burn the skin. 

 It is of particular value 

 to disinfect skin wounds, 

 as it heals as well as 

 cleanses when used in a 

 weak sol ution . Its rat her 

 pleasant odor makes it 

 useful to cover up un- 

 pleasant smells of the 

 sick room. 



The fumes of burning 

 sulphur, which are so 

 often used for disinfect- 

 ing, are of little real 

 value. 



Bacteria cause Decay. 

 Let us next see in 

 what ways the bacteria 

 directly influence man 

 upon the earth. Have 

 you ever stopped to con- 

 sider what life would be 

 like on the earth if things did not decay ? The sea would soon be 

 filled and the land covered with dead bodies of plants and animals. 

 Conditions of life would become impossible and living things on 

 the earth would cease to exist. 



Fortunately, bacteria cause decay. All organic matter, in 



IT R-A.TES 



This shows how organic matter is broken down 

 by bacteria so it may be used again by green 

 plants. 



