Lesions 



331 



to 6o°C. The spores, on the other hand, resist drying and exposure 

 to the atmosphere well and can be kept alive for years in garden 

 earth. The complete destruction of the spores requires exposure to 

 90°C. for a half hour. Moist heat at ioo°C. kills them in a few 

 minutes. 



Metabolic Products. — Of the toxic products of the organism 

 nothing definite is known. It decomposes albumin, forming fatty 

 acids, leucin, hydroparacumaric acid, and an oil with an offensive 

 odor. Among the gases formed, carbonic acid, hydrogen, and marsh 

 gas have been detected. 



Pathogenesis. — When introduced beneath the skin, the bacillus 

 is pathogenic for a large number of animals — mice, guinea-pigs, 

 rabbits, horses, dogs, sheep, goats, pigs, calves, chickens, and 

 pigeons. Cattle seem to be immune. 



Giinther points out that the simple inoculation of the bacillus upon 

 an abraded surface is insufficient to produce infection, because the 



Fig. 118. — Bacillus oedematis, dextrose gelatin culture (Giinther). 



presence of oxygen is detrimental to its growth. When the bacilli 

 are deeply introduced beneath the skin, infection occurs. 



Mice, guinea-pigs, and rabbits sicken and die in about forty-eight 

 hours. 



Washed spores of the bacillus are quickly taken up by phagocytes 

 and destroyed without producing infection. Salt-solution suspen- 

 sions of such spores quickly infect, however, if mixed with some 

 tissue-injuring agent such as lactic acid, or if combined with a 

 harmless micro-organism such as Bacillus prodigiosus by which the 

 phagocytic activity of the leukocytes is distracted through preference. 



Lesions. — In the blood the bacilli are few because of the loosely 

 combmed oxygen it contains. The great majority of the bacilli 

 occupy the subcutaneous tissue, where very little oxygen is present 

 and the conditions of growth are good. The autopsy shows a 

 marked subcutaneous edema containing immense numbers of the 



