36 Structure and Classification of Micro-organisms 



an incasement of almost cartilaginous consistence, have been called 

 Leuconostoc. 



Bacilli.— Better known, if not more important, bacteria consist of 

 elongate or "rod-shaped forms," and bear the name Bacillus (a rod). 

 These present considerable variation of form. Some are ellipsoid, 

 some long and slender. Some have rounded ends, as Bacillus 

 subtiUs; others have square ends, as B. anthracis. Some are large, 

 some exceedingly small. Some always occur singly, never uniting 

 to form threads or chains; others are nearly always so conjoined. 



y \. 



-^ 







{ 



w^^^^ 



f' 



230 ■■■ 



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3 

 Fig. 5. — Various forms of spiral organisms (Kolle and Wassermann) . 



The bacilli divide by transverse fission only, so that the only 

 peculiarity of arrangement is the formation of threads or chains. 

 In the older writings, short, stout bacilli were described under the 

 generic term Bacterium. Migula now employs the term to include 

 only bacillary forms without flagella. * A Fseudomonas is a baciUary 

 form with polar flagella. Some of the flexile bacilli have sinuous 

 movements resembling the swimming of a snake or an eel, and are 

 sometimes described as Vibrio; but this name also has passed into 

 disuse, except in France. 



