The organism is a large bacillus having an average size of 4 to 8 μ in
length by 0.5 to 0.7 μ in thickness, but there are many longer forms
measuring from 10 to 20 μ in length. It develops in long, irregular
chains or filaments, which at times show a slightly spiral form.
[Illustration:
FIG. 5.—Ham-souring bacillus (_Bacillus putrefaciens_) grown
on egg-pork medium, showing tendency to form chains. Partly
developed and fully developed spores are shown at ends of rods;
also free spores. (Pen-and-ink drawing made with camera lucida
from preparation stained by Gram’s method. × 640.)]
The individual organisms show at times a widely open, slightly spiral
form, which was more apparent in hanging-drop preparations made
from bouillon cultures, where the organisms had been comparatively
undisturbed. This appearance was also noted at times in the stained
sections of soured muscular tissue, where the organisms were stained in
place. The organism possesses no motility. It stains with the ordinary
aniline dyes and by Gram’s method.