CHAPTER 1 



THE NATURE, STRUCTURE, AND FUNCTIONS OF THE 

 BACTERIA: THEIR CLASSIFICATION, GENERAL BIO- 

 LOGY, AND CHEMISTRY BACTERIA AND DISEASE 



THE Bacteria or Schizomycetes (" fission fungi ") are 

 minute vegetable organisms for the most part unicellular 

 and devoid of chlorophyll, which multiply by simple trans- 

 verse division or fission ; this distinguishes them from the 

 yeasts, in which multiplication takes place by budding or 

 gemmation. A certain number of filamentous forms are 

 also included, serving to connect the unicellular ones with 

 the multicellular true fungi. The " fission plants " may 

 be placed in a sub-kingdom, the Schizophyta, which 

 may be divided into two classes : Class I, Schizophycese, 

 the blue-green algae, and Class II, Schizomycetes, the 

 bacteria. 



The unicellular plants are sometimes termed the " Proto- 

 phyta." It must be understood that there are connecting 

 links between the different groups, and that there is no 

 sharp line of demarcation between them. 



The relation of the bacteria to other lower plants is 

 shown in the following scheme (p. 9) : 



The Bacteria have been supposed to have affinities with 

 the Fungi, with the Protozoa, or with the Cyanophycese. 

 There is little or no evidence to connect them with the first 

 two groups and not much with the last one, though the 

 resemblances here are greater. Though usually regarded 

 as simple forms, the Bacteria display considerable morpho- 



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