570 BACTERIOLOGY. 



conditions of growth they may develop into long, spiral 

 filaments, which may consist of numerous spiral turns 

 in which it is impossible to recognize any connection 

 with the individual elements of which they are made 

 up. In stained preparations the spiral character of the 

 long filaments is often obliterated, or nearly so. Under 

 favorable conditions of growth that is, when the 

 growth is rapid the short-curved or almost straight 

 forms are commonly observed (Figs. 74 and 75). In 

 old cultures involution forms are frequent. 



Stains with the aniline colors usually employed, but 

 not as readily as many other bacteria; an aqueous solu- 

 tion of carbol-fuchsin is recommended as the most reli- 

 able staining agent with the application of a few minutes' 

 heat. It is decolorized by Gram's method. The motile 

 organs exhibit one or two long, fine, spiral flagellse 

 attached to one end of the rods. 



Biological Characters. An aerobic (facultative ana- 

 erobic), liquefying, motile spirillum. Grows readily in 

 the ordinary culture media, best at 37 C., but also at 

 the room-temperature (22 C.); does not grow at a tem- 

 perature above 42 or below 8 C. Does not form 

 spores. 



In gelatin plate cultures, at 22 C., at the end of 

 twenty-four hours, small, round, yellowish-white to yel- 

 low colonies may be seen in the depths of the gelatin, 

 which later grow toward the surface and cause liquefac- 

 tion of the medium, the colonies lying at the bottom of 

 the holes or pocket thus formed. The zone of lique- 

 faction, which increases rapidly, remains at first clear, 

 then becomes cloudy, mostly gray, as the result of the 

 growth of the colonies. In many cases after a time 

 concentric rings, which increase from day to day, appear 



