94 MORPHOLOGY OF THE BACTERIA. 



g. Spirillum, Ehrb. 



Filament spiral, rigid; turns of spiral short 

 and regular. 



S. tenue, Ehrb. 



Filament slightly tortuous, three to four turns of 

 the spiral ; length and diameter of a single turn, 2 to 

 3 fi. When the filament has a turn and a half, it re- 

 sembles an fl ; the filaments of two to five turns have 

 a length of 4 to 15 /a ; spiral movement very rapid. 



In infusions, etc. 



S. undula, Ehrb. (Vibrio prolifer, Ehrb.) 



Filament larger, turns of the spiral wider apart 

 (from 3 to 5 /a) ; having usually one half a turn to 

 one full turn, rarely one and a half, two, or three ; 

 length 8 to 10 fi, breadth 5 /x, thickness of filament 

 1.3 fi ; having a very rapid spiral movement. 



Fetid animal and vegetable infusions and run- 

 ning water. 



The S. rufum, Pertz only differs from this by its reddish 

 color. 



S. volutans, Ehrb. 



Filament large and thick, turns of spiral regular, 

 well separated, and 13 p in height ; number of turns 

 two, three, and three and a half, rarely six and seven ; 

 total length 25 to 30 ft, thickness 1.5 fi, breadth 6.6 fi; 

 movement sometimes rapid, sometimes motionless ; 

 a well-defined ciliurn, already seen by Ehrenberg 

 (Cohn, Warming). 



This giant of the bacteria is found in vege- 

 table and animal infusions, in sea-water, and in 

 fresh water. 



