BACTERIA 



PART I 

 GENERAL CONSIDERATIONS 



CHAPTER I 



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BACTERIA 



THE bacteria occupy the lowest plane of plant life known to 

 us, though they are by no means as primitive in their biology 

 as was formerly supposed, and it is quite possible that still 

 simpler forms may be discovered. 



The numerous unicellular vegetable organisms which form 

 the lower limit of plant life as we know it multiply by fission 

 and are hence called the Schizophyta, or splitting plants. This 

 group is subdivided into two classes (a) the Schizophycece, or 



-rX 



a b c 



Fig. i. Types of bacteria: a, Micrococcus; b, spirillum; c, bacillus. 



fission algae, and (6) the Schizomycetes, or fission fungi, or 

 bacteria, as we usually call them. 



Bacteria are unicellular masses of protoplasm of micro- 

 scopic size, multiplying by fission and existing without chloro- 

 phyl. Three main types are found: (i) Globular forms, 

 called cocci; (2) straight rod-shaped forms, called bacilli; (3) 

 curved or spiral rods, called spirilla. (See Fig. i.) 



Structure. Bacteria are cells; they appear as round or 

 cylindric, of an average diameter on transverse section of o.ooi 



