IN SUSCEPTIBLE ANIMALS. 435 



studied in cultures and by experimental inoculations by Selander, 

 Billings, Frosch, Welch, Caneva, Bunzl-Federn, and others. 



The bacillus is found in the blood and various organs of hogs 

 which have succumbed to the infectious disease known in this country 

 as hog cholera ; and also in the contents of the intestine, from which 

 it may be obtained by inoculations into rabbits, but is not easily iso- 

 lated by the plate method owing to the large number of other bac- 

 teria present (Smith). 



Morphology. Short bacilli with rounded ends, 1.2 to 1.5 yu in 

 length and 0.6 to 0.7 /* in breadth ; usually united in pairs. 



This bacillus is easily stained by the aniline colors usually em- 

 ployed, but does not retain its color when treated by Gram's method. 

 When the staining agent is allowed to act for a very short time the 



FIG. 131. Bacillus of hog cholera; stained by Loffler's method to show flagella. x 1,000. From 

 a photomicrograph made at the Army Medical Museum. (Gray.) 



ends of the rods may be stained while the central portion remains 

 unstained. 



Biological Characters. An aerobic (facultative anaerobic), non- 

 liquefying, actively motile bacillus. In many of its characters this 

 bacillus closely resembles the one last described (Bacillus septicaemias 

 hsemorrhagicse), but it is distinguished from it by its active move- 

 ments, which, according to Smith, may be still observed in cultures 

 which have been kept for weeks or months. Does not form spores. 

 Grows readily in various culture media at the room temperature 

 more rapidly in the incubating oven. Upon gelatin plates colonies 

 are developed in from twenty-four to forty-eight hours. The deep colo- 

 nies are spherical and homogeneous, and have a brownish color by 

 transmitted light; they seldom exceed one-half millimetre in diameter. 



