NOT DESCRIBED IN PREVIOUS SECTIONS. 549 
varying greatly in length, being sometimes short oval, and at others 
from 1.25 to 3.75 jv in length ; also grow out into flexible filaments, 
which may be more or less wavy or spiral in form. The short rods 
are commonly seen in pairs ; they have terminal flagella ; involution 
forms are frequently seen, the most common being spherical bodies 
about 1.6 in diameter. In old cultures in bouillon, or in cultures 
made in meat infusion in the incubating oven, the short oval forms 
greatly predominate, but in recent cultures in nutrient gelatin fila- 
ments of considerable length are encountered in association with 
shorter rods. 
Stains readily with fuchsin or gentian violet—not so well with 
the brown aniline colors ; does not stain by Gram’s method (Cheyne). 
Biological Characters.—An aérobic and facultative anaérobic, 
liquefying, motile bacillus. Grows rapidly in. the usual culture 
media at the room temperature. 
The growth upon gelatin plates (five per cent of gelatin) at the 
room temperature is very characteristic ; at the end of six or eight 
hours small depressions in the gelatin are observed, which contain 
liquefied gelatin and grayish-white masses of bacilli. Under alow 
power these depressions are seen to be surrounded by a marginal 
zone consisting of two or three layers, outside of which is a zone of a 
single layer, from which amceba-like processes extend upon the sur- 
face of the gelatin. These processes are constantly undergoing 
changes in their form and position, and may become separated from 
the mother colony, or remain temporarily attached to it by a narrow 
thread consisting of bacilli; after a time the entire surface of the 
gelatin is covered with wandering, amceba-like colonies; these 
rapidly cause liquefaction, which by the end of twenty-four to forty- 
eight hours has reached a depth of one millimetre or more over the 
entire surface. The deep colonies also are surrounded by processes 
projecting into the gelatin, which may be observed to suddenly ad- 
vance and again to be retracted towards the central zodgloea-like 
mass. Liquefaction around the colony rapidly progresses, and 
actively motile rods and spiral filaments may be seen about the peri- 
phery of this liquefied gelatin, while about it is a radiating crown of 
irregular processes, some of which may be screw-like or corkscrew- 
formed. In ten-per-cent gelatin the migration of surface colonies, 
above described, is not observed. In gelatin stab culturcs liquefac- 
tion occurs along the entire line of puncture, and soon the contents 
of the tube are completely liquefied ; near the surface of the liquefied 
gelatin the growing bacilli form a grayish-white cloudiness, and at 
the bottom of the tube an abundant flocculent deposit is formed. 
Upon the surface of nutrient agar a rapidly extending, moist, thin, 
grayish-white layer is formed. Upon potato this bacillus produces a 
