602 Micro-organisms of the Plague Group 



the related species, not possessed of flagella, incapable of 

 movement, and producing no spores. 



It is an optional anaerobe. 



Staining. The bacillus stains by the ordinary methods, 

 sometimes only at the poles, then closely resembling the 

 bacillus of chicken-cholera. It is not colored by Gram's 

 method. 



Cultivation. In general, the appearance in culture-media 

 is very similar to that of the hog cholera bacillus. Kruse,* 

 however, points out that when the bacillus grows in bouillon 

 the liquid remains clear, the bacteria gathering to form a 

 flocculent, stringy sediment. The organism does not grow 

 upon ordinary acid potato, but if the reaction of the me- 

 dium be alkaline, a grayish-yellow patch is formed. In milk 

 a slight acidity is produced, but the milk is not coagu- 

 lated. 



Vital Resistance. The vitality of the organism is low, 

 and it is easily destroyed. Salmon says that it soon dies in 

 water or when dried, and that the temperature for its growth 

 must be more constant and every condition of life more 

 favorable than for the hog-cholera germ. The organism is 

 said to be widely distributed in nature, and is probably 

 present in every herd of swine, though not pathogenic except 

 when its virulence becomes increased or the vital resistance 

 of the animals diminished by some unusual condition. 



Pathogenesis. While similar to hog-cholera, swine- 

 plague presents some marked differences, especially in 

 regard to the seat of the local manifestations, and in its 

 duration, which is much shorter. There is also considerable 

 resemblance to chicken-cholera, but the local reaction fol- 

 lowing the injection of the micro-organisms partakes of the 

 nature of a hemorrhagic edema, which is not present in 

 chicken-cholera, and rabbits commonly exhibit fatty meta- 

 morphosis of the liver. 



Rabbits, mice, and small birds are very susceptible to 

 the disease, usually dying of septicemia in twenty-four 

 hours; guinea-pigs are less susceptible, except very young 

 animals, which die without exception. Chickens are more 

 immune, but usually succumb to large doses. Hogs die of 

 septicemia after subcutaneous injection of the bacilli. There 

 is a marked edema at the point of injection. If injected 

 into the lung, a pleuropneumonia follows, with multiple 

 * Fliigge's "Die Mikroorganismen," p. 419, 1896. 



