512 BACILLI WHICH PRODUCE SEPTICAMIA 
slender and on the average shorter than the bacillus of mouse septi- 
cemia. The bacilli are solitary, or in pairs the elements of which 
are often united at an angle ; occasionally a chain of three or four 
elements may be observed, and in old cultures the bacilli may 
grow out into short threads which are straight or more or less 
curved and twisted. Small refractive bodies may sometimes be dis- 
tinguished in the rods, and these have been supposed by some authors 
to be spores, but this has not been demonstrated. 
This bacillus stains readily with the ordinary aniline staining 
agents and also by Gram’s method. 
Biological Characters.—A facultative anaérobic, non-liquefy- 
ing bacillus. According to Schottelius, the rothlauf bacilli are some- 
Fig. 134.—Bacillus of rouget, from a pure culture. x 1,000. Froma photomicrograph. (Roux.) 
times motile, but Fligge states that other observers have not seen 
them in active motion. Frankel says they have the power of volun- 
tary motion. Eisenberg says that the bacillus of mouse septiceemia 
is motionless, and Frankel says they “seem to be incapable of volun- 
tary motion.” Baumgarten remarks: “ Whether the bacilli exhibit 
voluntary movements has not been determined.” Although this 
bacillus is not strictly anaérobic, it grows better in the absence of 
oxygen than in its presence. Development occurs in various culture 
media at the room temperature, but is more rapid in the culture 
oven. In gelatin stab cultures no development occurs upon the 
surface, but the growth along the line of puncture is very character- 
istic; this consists of a delicate cloud-like, radiating growth, which 
extends, in the course of a few days, almost to the walls of the test 
tube. The rothlauf bacillus does not extend so rapidly through the 
