104 BACTERIOLOGY. 



establishing- these microscopic objects as members 

 of the vegetable kingdom, ranking among the 

 lowest forms of fungi. While enabling us to settle 

 their position as a whole, these improved methods 

 have further given us so great an insight into the 

 life-history of individual forms, that, with regard 

 to the division into genera and species, we are 

 up to the present time still in a position of doubt 

 and uncertainty. 



Miiller, in 1773, was the first to suggest a classi- 

 fication. He established two genera, Monas and 

 Vibrio, and grouped them with the Infusoria. In 

 1824 Bory de Saint Vincent also attempted a classi- 

 fication ; but it was not until Ehrenberg in 1838, 

 and Dujardin 'in 1841, worked at the subject, that 

 a scientific distinction of species was attempted. 



Ehrenberg described four genera : 



I. Bacterium . . filaments straight, rigid. 



II. Vibrio . . filaments snake-like, flexible. 



III. Spirillum . . filaments spiral, rigid. 



IV. Spirochsete . . filaments spiral, flexible. 



Dujardin united Spirillum and Spirochate, and 

 classed them thus : 



I. Bacterium . filaments rigid, vacillating. 

 II. Vibrio . . filaments flexible, undulatory. 

 III. Spirillum. . filaments spiral, rotatory. 



Up to that time bacteria were still considered as 



