Lesions 



341 



9o°C. for a half hour. Moist heat at ioo°C. kills them in a few 

 minutes. 



Metabolic Products. — The organism decomposes albumin, forming 

 indol, HaS, fatty acids, leucin, hydroparacumaric acid, and an oil 

 with an offensive odor. It liquefies gelatin and digests blood-serum. 

 It ferments dextrose with the evolution of carbonic acid, hydrogen, 

 and marsh gas. 



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. 115. — Bacillus cedematis, 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 

 combined 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 

 bacilli. If the animal be permitted to remain undisturbed for some 

 time after death, the bacilli spread to the circulatory system and 

 reach all the organs. 



