392 



BACTERIA 



Rod-shaped bacteria, baci'Ji, sometimes occur singly. They may form strings and are then 

 known as streptobacilli. They sometimes have projections of protoplasm, somewhat similar 

 to cilia, called flagella. 





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Spherical bacteria, cocci, may occur in pairs, diplococci; or in chains, streptococci; or in clus 



ters, staphylococci. 



The spiral bacteria, spirilla, may not have flagella, or they may have them. These bacteria 



are always recognized by their twisted shape. 



motile bacteria and are able to move through the water by means 

 of these structures. 



There are many different species of bacteria. Most of them 

 may be grouped as one of three forms. These are the bacilli 

 or rod-shaped bacteria, the cocci or spherical, and the spirilla or 

 spiral. Bacteria vary greatly in size and shape within the same 

 group, although they are all microscopic. The micron is the unit 

 of measurement in microscopic work. It is about one-thousandth 



