1 88 BACTERIOLOGY. 



It has already been mentioned that the produc- 

 tion of arthrospores is only established in a very 

 few species. Therefore, we are hardly justified in 

 assuming that all bacteria, the spore-formation of 

 which is quite unknown, are to be included with 

 those in which this kind of fructification has been 

 observed, and consequently to distinguish genera 

 on the same grounds may be considered, to say the 

 least, somewhat premature. In Baumgarten's classi- 

 fication the genus bacterium is dispensed with, and 

 the genera divided into two groups, the mono- 

 morphic and the pleomorphic. 



GROUP I. MONOMORPHIC. 

 Genera . Coccus. 

 Bacillus. 

 Spirillum. 



GROUP II. PLEOMORPHIC. 

 Genera. Spirulina. 

 Leptothrix. 

 Cladothrix. 



Flugge also, in his recent classification, includes 

 the genus bacterium in the genus bacillus. The 

 new classification differs also from the original one 

 in the grouping together of the different species 

 according to the character and behaviour of the 

 colonies in nutrient gelatine. The abolition, in 

 Fliigge's and Baumgarten's classification, of the 

 genus bacterium is no doubt owing to confusion 

 having arisen from the distinction between a 



