1 86 ESSENTIALS OF BACTERIOLOGY 



not found in the viscera, but are present in great numbers on 

 the surface, i. e., in the serous coverings of the different organs; 

 though when any length of time has elapsed between the 

 death of the animal and the examination, they can be found 

 in the inner portions of the organs, for they grow well upon 

 the dead body. In man they have been found in rapidly 

 spreading gangrene following wounds. 



Habitat. They are present in the soil, in putrefactions of 

 various kinds, and in dirty water. 



Immunity. Is produced by injection of the sterilized cul- 

 tures, and also the filtered blood-serum of animals dead with 

 the disease. 



Bacillus Aerogenes Capsulatus (Welch, 1891). 

 Synonym. Bacillus Welchii; B. of Phlegmonous Emphysema 

 (Frankel). 



Origin. The intestine of man and animals, soil, sewage, 

 and water. 



Form. A thick bacillus, 3 to 6 ju in length, frequently 

 capsulated. 



Properties. Not motile, anaerobic, forms spores chiefly in 

 cultures on blood-serum. Gram positive. 



Growth. Best at 37 C. 



Gelatin. Liquefied slowly or not at all. 



Bouillon. Forms gas. 



Milk. Coagulated and becomes acid. Under anaerobic 

 conditions. 



Potato. Thin, grayish-white growth with gas-production. 



Forms gas in abundance in dextrose, lactose, or saccharose 

 media. 



Pathogenesis. Is not usually pathogenic for rabbits and 

 mice, though in guinea-pigs and birds it produces "gas phleg- 

 mons." It is sometimes found in autopsies on human sub- 

 jects, producing bubbles or cavities in the viscera (Schaum- 

 organe), but this is probably due to postmortem migration 

 of the germ from the intestine. It has been recovered from 

 the blood during life, however, and is the most frequent 

 cause of emphysematous gangrene. In man, infection of 

 wounds, through dirt, with this bacillus causes rapid emphy- 



