ANAEROBIC BACTERIA 189 



Staining. Ordinary methods. Gram's method is nega- 

 tive, but the spores can be colored by the regular double stain 

 for spores. 



Sugar Media. Gas production. 



Milk. Rendered acid and coagulated. 



Variability. Great variation in cultures. 



Toxin elaborated in fluid media fatal for rabbits when 

 injected intravenously. 



Pathogenesis. If a small amount of the culture be injected 

 under the skin of a guinea-pig, in twenty hours a rise of tem- 

 perature, pain at the site of injection, and a few hours later 

 death, occur. At the autopsy, the tissues are found black- 

 ened in color and soaked with a bloody, serous fluid; in the 

 connective tissue large collections of gas, but only in the neigh- 

 borhood of the point of infection. The bacilli are found in 

 great numbers in the serum, but only appear in the viscera 

 some time after death, when spores have developed. 



The animals are usually infected through wounds on the 

 extremities; the stalls or meadows having been soiled by the 

 spore-containing blood of animals previously dead of the dis- 

 ease. " Ratischbrand" is the German name; "Charbon symp- 

 tomatique" the French, from the resemblance in its symp- 

 toms to anthrax. 



Feeding experiments and infection from animal to animal 

 negative. 



Dried virus inoculation practised by the United States 

 Government as preventive. 



Immunity. Rabbits, dogs, pigs, and fowl are immune by 

 nature, but if the bacilli are placed in a 20 per cent, solution of 

 lactic acid and the mixture injected, the disease develops in 

 them. The lactic acid is supposed to destroy some of the 

 natural resistance of the animal's cells. 



Immunity is produced by the injections of these weakened 

 cultures, and also by some of the products which have been 

 obtained from the cultures. 



