92 MORPHOLOGY OF THE BACTERIA. 



veloped, from the Vibrio rugula, which only pre- 

 sents a single curve in its centre, to certain species 

 of Spirillum which have numerous turns of the 

 spiral. In several species, cilia, or a flagellum, have 

 recently been observed. 



We divide them into three genera : — 



Fil. short, slightly sinuous . . . Vibrio. 

 Fil. short, spiral, rigid .... Spirillum. 

 Fil. long, spiral, flexible .... Spirochete. 



g. Vibrio, Auct. emend. 



Body filiform, more or less distinctly articu- 

 lated, always undulating, having serpentine 

 movements. This genus forms the transition 

 between the Desmobacteria and Spirillum "from 

 which it cannot be separated " (Warming). 



Fil. thick, with a single curve ... V. rugula. 

 Fil. slender, with several undulations . V. serpens. 



V. rugula, Miiller (V. lineola, Duj. ex parte). 



Filament presenting in its centre a single curva- 

 , ture, feeble but distinct ; length 8 to 16 /u.. The 

 shortest are slightly curved (= 6 fx, Warming), the 

 larger, which may attain 17.6 fi (Cohn), 35 /a (Warm.), 

 are about to divide. Movements of rotation more or 

 less rapid around their longer axis ; of progression 

 forward, giving then the idea of a serpentine move- 

 ment: having a cilium (Warming). 



V. rugula is commonly found in swarms, in 

 infusions, in deposits upon the teeth, in intes- 

 tinal matters (Leewenhoeck), in choleraic dis- 

 charges (Pouchet). 



