Pathogenesis 607 



disease that not infrequently occurs in association with hog- 

 cholera (q. -u.), and because of the lack of sufficiently well- 

 characterized symptoms sick hogs appearing more or less 

 alike is often mistaken for it. The confusion resulting 

 from such faulty diagnosis makes it difficult to determine 

 exactly how fatal either disease may be in uncomplicated 

 cases. 



Morphology. The bacillus of swine-plague much re- 

 sembles that of hog-cholera, and not a little that of chicken- 

 cholera. It is a short organism, rather more slender than 

 the related species, not possessed of flagella, incapable of 

 movement, and producing no spores. 



In its growth the bacillus of swine-plague 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 

 medium 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, to which 

 attention has already been called, and in its duration, 

 which is much shorter. There is also considerable re- 

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

 * Fliigge's "Die Mikroorganismen,' 1 p. 419, 1896. 



