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 the skin is not sufficient 

 to produce infection; owing to the bacillus being capable 

 only of an anaerobic existence, the poison must pene- 

 trate deep into the tissues. Malignant oedema is con- 

 fined 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 injecting filtered cultures of 

 the malignant oedema bacillus in harmless quantities. 



BACILLUS AEROGENES OAPSULATUS. 



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, as a 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 



35 



