504 



BACILLI WHICH PRODUCE SEPTICAEMIA 



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 septicaBmise 

 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. 



FIG. 132. 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.) 



The superficial colonies may attain a diameter of two millimetres ; 

 they present no distinctive characters. Upon agar plates the colonies 

 may have a diameter of four millimetres ; they have a grayish, trans- 

 parent appearance and a shining surface. In gelatin stab cultures 

 small, yellowish-white colonies are developed along the line of in- 

 oculation, which may become confluent ; upon the surface a thin, 

 pearly layer is developed about the point of inoculation, which may 

 have a diameter of six millimetres or more. Upon potato a straw- 

 yellow layer is developed, which later acquires a darker color. In 

 slightly alkaline bouillon a slight cloudiness may be observed at the 

 end of twenty-four hours, and at the end of one or two weeks, if 

 not disturbed, a deposit is seen at the bottom of the tube and a thin, 

 broken film may form upon the surface. The development of this 

 bacillus in milk produces a direct solution of the casein without pre- 

 vious coagulation ; when a solution of litmus has been added to milk 



