BACILLUS AEROGENES CAPSULATUS. 545 
little, if any, production of gas. In infection with 
garden earth, owing to the presence of associated ba- 
cilli, the effused serum is frothy from the development 
of gas, and possesses a putrefactive odor. The disease, 
in natural infection caused by the contamination of 
wounds with earth or feces, runs the course above de- 
scribed. Simple abrasion of tbe skin is not sufficient 
to produce infection; owing to the bacillus being capable 
only of an anaérobic existence, the poison must pene- 
trate deep into the tissues. Malignant cedema is con- 
fined mostly to the domestic animals, but cases have 
also been reported in man. 
Animals which recover from malignant cedema are 
subsequently immune. Artificial immunity may be 
induced in guinea-pigs by injecting filtered cultures of 
the malignant cedema bacillus in harmless quantities. 
BACILLUS AEROGENES CAPSULATUS. 
Found by Welch in the bloodvessels of a patient 
suffering with aortic aneurism; on autopsy, made in 
cool weather eight hours after death, the vessels were 
observed to be full of gas-bubbles. Since then it has 
been found in a number of cases in which gas has de- 
veloped from within sixty hours of death until some 
hours after death. These cases are, asa rule, marked by 
delirium, rapid pulse, high temperature, and the devel- 
opment of emphysema and discoloration of the diseased 
area, or of marked abdominal distention when the peri- 
toneal cavity is involved. 
Morphology. Straight or slightly curved rods, with 
rounded or sometimes square-cut ends; somewhat 
thicker than the anthrax bacilli and varying in length; 
occasionally long threads and chains are seen. The 
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