380 BACTERIA PATHOGENIC TO MAN 



goats, sheep, calves, pigs, chickens, and pigeons are also susceptible. 

 A small quantity of a pure culture injected beneath the skin of a sus- 

 ceptible animal gives rise to an extensive hemorrhagic oedema of the 

 subcutaneous connective tissue, which extends over the entire surface 

 of the abdomen and thorax, causing hypersemia and redness of the 

 superficial muscles. No odor is developed, and there is little, if any, 

 production of gas. In infection with garden earth, owing to the pres- 

 ence of associated bacilli, the effused serum is frothy from the develop- 

 ment 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 described. Simple abrasion of the skin is not 

 sufficient to produce infection; owing to the bacillus being capable only 

 of an anaerobic existence, the poison must penetrate deep into the 

 tissues. Malignant oedema is confined mostly to the domestic animals, 

 but cases have also been reported in man. 



Animals which recover from malignant oedema are subsequently 

 immune. Artificial immunity may be induced in guinea-pigs by inject- 

 ing filtered cultures of the malignant oedema bacillus in harmless quan- 

 tities. 



In man the chief symptom is the sudden appearance of an oedematous 

 swelling accompanied by high fever. In light cases this remains cir- 

 cumscribed; in severe cases it spreads widely and the case ends fatally. 

 Autopsy shows a serous or hemorrhagic infiltration of the subcutaneous 

 tissues and intramuscular connective tissue. In the inflamed tissue 

 the bacilli with and without spores are found. 



Bacillus Aerogenes Capsulatus. 



This bacillus was found by Welch in the bloodvessels of a patient 

 suffering with aortic aneurysm ; 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 developed from within sixty hours of death until some hours after 

 death. These cases are, as a rule, marked by delirium, rapid pulse, 

 high temperature, and the development of emphysema and discolora- 

 tion of the diseased area, or of marked abdominal distention when the 

 peritoneal 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 bacilli in the animal body, and sometimes in cultures, are enclosed 

 in a transparent capsule. 



Biology. An anaerobic, non-motile, non-liquefying bacillus. Does 

 not form spores. Growth is rapid at 37 C., in the usual culture media 

 in the absence of oxygen, and is accompanied by the production of 

 gas. Nutrient gelatin is not liquefied by the growth of this bacillus, 

 but it is gradually peptonized. In agar colonies "are developed which 

 are from 1 to 2 mrn. or more in diameter, grayish-white in color, and 



