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 flagelle 
attached to one end of the rods. 
Biological Characters. An aérobic (facultative ana- 
érobic), 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 
