18 THE BACTERIA. 



vibrios with Leptothrix. This opinion, which 

 was not favorably received by the authors who 

 adopted nearly all of the generic groups of Ehren- 

 berg and Dujardin, is to-day accepted by many 

 botanists, above all since the labors of Cohn. (See 

 below: classification.) At all events, it is to M. 

 Davaine (1859) that we are indebted for clearly 

 pointing out that the vibrioniens are vegetables, 

 nearly allied to the algae, and especially to the 

 confervae. 



This same author, having observed some mo- 

 tionless bacteria, thought it necessary to give 

 this character great consideration, and to estab- 

 lish a fourth group, the genus Bacteridium, which 

 he added to the three others admitted by Dujar- 

 din ; but in this creation he was less happy than 

 in his placing the vibrioniens among the vege- 

 tables ; for we shall see further on that this char- 

 acter of mobility or of immobility is not absolute, 

 and that it depends upon the age of the bacterium 

 or upon certain conditions relating to the medium 

 in which it is placed. 



The most recent complete exposition of the 

 classification and of the ideas of M. Davaine is 

 found in the " Dictionnaire Encyclop. des Sci- 

 ences Me"dieales," art. BacteVies (1868). It may 

 be summed up as follows : — 



Filaments straight \ Moving sponta- ) Kigid. . Bacterium. 



or bent, but not V neously . . j Flexible . Vibrio. 



in a spiral . ) Motionless Bacteridium. 



Filaments spiral Spirillum. 



