BACILLUS .flROFCETIDUS 551 
Bacteriological Diagnosis. Morpholof/j/. — Tlie demonstration of 
(iram staining diplobacilli, with a clear space separating the individual 
cells, is of some diagnostic importance. Examined in the unstained 
condition, motility, the rapid formation of oval, terminal, or nearly 
terminal spores, and the tendency toward involution forms are import- 
ant features. 
Cultural.— The proteolytic powers of B. histolyticus, resulting in the 
digestion of gelatin, meat, casein and serum, are striking; the absence 
of fermentative reactions taken in association with the strong proteo- 
lytic activity distinguish B. histolyticus from practically all other 
anaeroix's. 
Pathogenesis. —The muscle digestion induced by the injection of \'ery 
young and active cultures (1 cc.) is the most striking and characteristic 
property of the organism. 
The agglutination of the bacilli with specific agglutinating sera 
affords a confirmatory test. 
BACILLUS ^ROF(ETIDUS. 
Bacillus aeroffjetidus was first isolated and described by Weinberg and 
Seguin^ in 1916. It has since been isolated from cases of gangrene by 
Henry.- * 
Morphology. — B. {lerofoetidus is a small, anaerobic bacillus with 
rounded ends which measures from 0.4 to 0.7 micron in diameter and 
from 2 to (i microns in length. It occurs singly, as a rule; occasionally 
]jairs of bacilli are found and, less commonly, short chains of :] to G 
elements. Motility, if present, is very slight and fiagella have not been 
demonstrated. Capsules have not been reported. 
Spores were not observed by Weinberg and Seguin, but other strains 
studied ha\e invariably sporulated in protein-rich media. The spores 
are slightly larger than the parent cell and subterminal in position. 
Young cultures retain the Gram stain. Older cultures become Gram- 
negative. The organism stains readily with ordinary anilin dyes. 
Isolation and Culture. — B. a?rofoetidus is not difficult to cultivate in 
ordinary media if oxygen is excluded. Colonies on agar are luxuriant; 
large (2 to 4 mm.), round growths with thicker centers and thinner 
edges. They resemble those of B. bifermentans in their general appear- 
ance. Submerged colonies are usually lenticular in outline, and com- 
paratively small. 
Conditions of Growth.— The organism is a member of the anaerobic 
group, less fastidious with respect to the diminution of oxygen tension 
in which it will grow than some of the other anaerobes. (Growth 
ceases above 43° C. and below 16° C. A reaction slightly on the 
alkaline side of neutrality (pii 7.5) is best adapted to its development 
in cultural media. 
• Compt. rend. Soc. de biol., 1916, 79, 116. 
2 Jour. Pathol, and Bacteriol., 1916-1917, 21, 367. 
