BACILLUS OF MALIGNANT EDEMA 247 



gas. It does not liquefy gelatin. In milk its growth is especially 

 characteristic : acid is rapidly formed, coagulation occurs, and soon 

 the clot becomes torn apart by gas bubbles, so-called " stormy 

 fermentation." Ultimately it forms an irregular firm mass in 

 the comparatively clear whey. The organism is a strict anaerobe. 

 Growth will occur at room temperature, but is most abundant at 

 37 C. 



Pathogenesis. In the lower animals infection seldom occurs. 

 In man the organism has been observed in diseases of the gastro- 

 intestinal and genito-urinary tracts. When such cases end fatally 

 the bacilli frequently pass into the blood stream at the time of 

 death and produce gas cavities in the various internal organs ; the 

 so-called " foamy organs " observed at autopsy. The bacillus 

 is of special interest in that it has been by far the most important 

 cause of gas gangrene in war wounds. Laceration of the muscle 

 tissue with an object contaminated with soil containing the bacillus 

 is usually the starting point of infection. The remarkable feature 

 of the disease is the rapidity with which it spreads. Cases have 

 been recorded in which emphysematous swelling and gangrene of 

 a limb has ended fatally within twenty-four hours. 



BACILLUS OF MALIGNANT EDEMA 



The organism was first discovered by Pasteur in 1877 in putrid 

 flesh. He found that by introducing such flesh into rabbits an 

 edematous condition of the tissues and degenerative changes in 

 the various organs were produced. Koch and Gaffky in 1881 

 isolated the organism, carefully studied it, and gave to it the name 

 B. edematis maligni. The organism is found in the intestinal 

 tract of the higher animals, in the upper layer of the soil in putre- 

 fying substances, and in polluted water. During the recent war 

 it was found in putrid wounds and cases of gas gangrene next in 

 order of frequency to B. Welchii. 



Morphology and Staining. The bacilli vary in length from 2 

 to 10 p and 0.8 to 1 /A in width. They are usually seen in pairs 

 joined end to end ; occasionally they occur in long chains. The 



