CLASSIFICATION OF BACTERIA. 1 93 



Thus the well-known Micrococcus proiigiosus, now 

 named by Fliigge and others as Bacillus prodigiosus, 

 is placed by the author as a bacterium, for it un- 

 doubtedly appears in the form of short rods, but 

 without endogenous spore-formation. 



Any arrangement at present can only be con- 

 sidered provisional, and, therefore, that arrangement 

 which is of most practical assistance, and which leads 

 to a clear description of the important characteristics 

 on which the final classification will depend, must 

 be considered to be the best. For example, if we 

 abolish the genus bacterium, any rod-form may be 

 at once classed as a bacillus ; on the other hand, 

 in the plan here adopted, we must determine the 

 presence or absence of endogenous spore-formation 

 before we can decide whether it be a bacterium or a 

 bacillus. This necessarily leads to a more thorough 

 study of their life-history. In the systematic de- 

 scription which follows, stress is laid upon the 

 morphological appearances of bacteria, upon the 

 absence or presence of spore-formation, and upon 

 the appearances under cultivation, in addition to 

 other characteristics, such as the changes produced 

 by their growth. The determination of species 

 rests upon the accumulated evidence afforded by 

 a thorough knowledge of their life-history. The 

 form of the organism, the changes it effects, and 

 the microscopical appearances under cultivation, 

 must be collectively taken into account. 



