CHAPTER XVIII. 

 BACTERIACE^: THE SPOROGENIC ANAEROBES. 



The bacteria of this group are hindered in their development 

 by the presence of free oxygen and their artificial culture is ordi- 

 narily successful only when they are protected from oxygen, at 

 least in the early stages of development. Like the sporogenic 

 aerobes, they live in the soil, but they are associated here more 

 especially with decomposing materials of animal origin, and are 

 less frequently found in soils which have not received fertilizers 

 from animal sources. There is good reason to believe that their 

 essential habitat is the intestinal canal of animals, especially the 

 mammals, and that their life in the soil does not represent the 

 most active stage of their existence, but that they reach the soil 

 with animal excreta and the bodies of dead animals and continue 

 to live in the soil for a considerable period. 



Bacillus Edematis. Pasteur in 1877 injected infusions of 

 putrid flesh into laboratory animals and produced a fatal sub- 

 cutaneous edema with penetration of the bacteria into the blood 

 in some instances. The organism which he called "Vibrion 

 septique" was found to be an obligate anaerobe, the first anae- 

 robic organism ever recognized. Koch (1881) studied the organism 

 in pure culture on solid media and named it Bacillus edematis 

 maligni. The recognized type organism is that studied by 

 Koch. 



The bacillus is very widely distributed in soil and dust, and 

 is very common in the feces of herbivorous animals. It is es- 

 pecially abundant in putrefying animal matter. The cell is about 

 i/x thick by 3/i in length, although considerable variation in size 

 and shape occurs. It is usually slightly motile and possesses 

 peritrichous flagella, stains readily, is only relatively Gram-posi- 



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