PART I 

 GENERAL BACTERIOLOGY 



CHAPTER I 

 STRUCTURE AND DEVELOPMENT OF 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 ultra- 

 microscope gives promise of such minute organisms, and 

 has made visible particles of matter yj-^ the size of our 

 smallest known bacteria. 



The numerous unicellular vegetable organisms which form 

 the lower limit of plant life multiply by fission and are 



a b c 



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



hence called the Schizophyta, or splitting plants. This 

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

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



.or bacteria, as we usually call them. 



TV Bacteria are unicellular masses of protoplasm of microscopic 

 size, multiplying by fission and existing without chlorophyl. 

 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.) 



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