PART VII. MAN'S CONTROL OF HIS ENVIRONMENT 

 IN RELATION TO HEALTH 



CHAPTER XXII 



BACTERIA AND DISEASE 



Problems: What are bacteria and how may we obtain and grow 

 them? 



What are conditions favorable and unfavorable to the growth of 

 bacteria? 



What are some means used to destroy bacteria? 



What are some diseases caused by bacteria? 



Laboratory Suggestions 



Problem. Where are bacteria found? 



Demonstration. How bacteria are grown. 



Demonstration. How to make culture media. 



Demonstration. How to obtain a pure culture of bacteria. 



Home experiment. Conditions favorable for the growth of bacteria. 



Demonstration. Effect of light on bacterial growth. 



Demonstration. Effect of heat on bacterial growth. 



Experiment. Use of disinfectants. 



What is Health ? — The body has been likened to an engine or 

 machine and we have found that in some respects this simile holds 

 true. The body and the engine are each made of many parts and 

 run more or less automatically. Both require fuel and oxygen to 

 do work, both produce wastes, and both must have frequent rest 

 if they are to do efficient work. Both the machine and the body 

 eventually may wear out ; and, if we carry the simile to the end, 

 both machine and body are destroyed. But we do not speak of a 

 sick machine, though we do speak of a sick person. What, then, 

 is health ? It is evidently a state in which the human machine runs 

 efficiently. It is a state of well-being, or being well. 



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