CHAPTER II. 



Classi- 

 fication of 

 bacteria 



Definition 

 of bac- 

 terium 



Structure 



THE CLASSIFICATION, MORPHOLOGY, BIOLOGY, AND 

 DISTRIBUTION OF BACTERIA. 



WE have referred to microorganisms as germs, 

 a popular term, but not exact enough for our use. 

 The term "germs" may be taken to mean any micro- 

 scopic organism, animal or vegetable. 



In the animal kingdom the lowest forms of life 

 are called Protozoa (sing. Protozoon), of which 

 there are several types: Sarcodina, Mastigophora, 

 and Sporozoa. The discussion of the protozoa will 

 be reserved until a later chapter. 



In the vegetable kingdom we are particularly 

 interested in the fungi, which are subdivided into 

 Hyphomycetes or molds, Blastomycetes or yeasts, 

 and Schizomycetes or bacteria. The bacteria are by 

 far the most important of the three; so we will con- 

 fine ourselves solely to them for the present, and 

 leave the yeasts and molds for a subsequent chapter. 



The word bacterium is derived from a Greek 

 word meaning a rod; the plural form is bacteria. A 

 bacterium may be defined as a minute living organ- 

 ism composed of one cell, belonging to the vegetable 

 kingdom. 



The structure of bacteria is very simple as we 

 know it. The vital part of the cell which controls 

 its activities is called the nucleus, and is usually situ- 

 ated at or near the center. Surrounding this is a 

 (6) 



