198 ESSENTIALS OF BACTERIOLOGY 



Agar at brood temperature, in twenty-four to forty-eight 

 hours, an abundant growth with a sour odor and abundant 

 gas-formation. 



Staining. Ordinary methods. Gram's method is negative, 

 but the spores can be colored by the regular double stain for 

 spores. 



Pathogenesis. If a small amount of the culture be injected 

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

 ture, pain at the site of injection, and in a few hours more 

 death occurs. At the autopsy, the tissues are found, blackened 

 in color and soaked with a bloody serous fluid; in the connective 

 tissue large collections of gas, but only in the neighborhood of 

 the point of infection. The bacilli are found in great num- 

 bers 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. " Rautehbrand" is the German name; "Charbon symp- 

 tomatique," the French, from the resemblance in its symptoms 

 to anthrax. 



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. 



When a bouillon culture is allowed to stand a few days, 

 the bacilli therein lose their virulence, and animals are 

 no longer affected by them; but if they are placed in 20 

 per cent, lactic acid and the mixture injected, their virulence 

 returns. 



Immunity is produced by the injections of these weakened 

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

 obtained from the cultures. 



Bacillus of Chicken Cholera (Pasteur). Synonyms 

 Micrococcus cholera gallinarum; Microbe en huit; Bacillus 

 amcidus; bacillus of fowl septicemia. 



