CHAPTER 1 



Introduction 



We are privileged to live in an age when, as the result of the hard 

 labors and the genius of men, a new world is opened up for our 

 studv— a fascinatinor, vibrant, sub-visible world hidden from the 

 eyes of human beings since the beginning of time. Since man first 

 viewed these interesting microorganisms, or germs, only about two 

 hundred years ago, much has been sacrificed, including the very 

 lives of some of the microbe hunters who have attempted to ferret 

 out the mysteries of these minute forms of life. 



It might be well at this point to distinguish between bacteria 

 and microorganisms. The former word includes only those single- 

 celled, non-chlorophyll-containing plants which multiply by binary 

 fission, or equal division. It may be a revelation to you to dis- 

 cover that bacteria are not "bugs," but plants. The word micro- 

 organism implies a much broader field and includes many different 

 microscopic forms of both plant and animal life, including molds, 

 yeasts, bacteria, protozoa, and even rickettsiae and viruses. Each 

 of these organisms will be considered separately in later chapters. 

 This book will deal principally with the bacteria, but because the 

 technics for studying the other microorganisms are similar to those 

 employed with bacteria, and because these other microscopic forms 

 are oftentimes found intimately associated with bacteria, we shall 

 not overlook them by any means. 



These organisms face many of the same problems confronting 



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