330 MICRO-ORGANISMS PATHOGENIC FOR ANIMALS ONLY. 



1 p. long and 0.2 fjt wide. Flagellation, motility, and sporula- 

 tion are doubtful. The bacillus is strongly inclined to be a 

 strict anaerobe. It can be cultivated at either the body or 



FIG. 145. 



FIG. 146. 



Colony of the bacillus of mouse septicaemia. X 80. (Fluegge.) 



room temperature. It stains with Gram and the usual anilin 



dyes. It is killed by a temperature of 52 C. in fifteen minutes. 

 The colonies on gelatin plates resemble the lacunae in bone 

 with their contents and processes (Fig. 145). 

 The colony is grayish in color, irregular, and 

 has many fine, wavy, branched projections. 

 The gelatin is gradually softened and evapo- 

 rated, the colonies coalescing to form a gray- 

 ish film. 



In gelatin stabs development takes place 

 along the entire needle-track, with little or 

 no surface growth. Usually the top of the 

 growth is slightly beneath the surface of the 

 medium. The growth in the gelatin tube is 

 peculiar. It resembles a column of discs, 

 each disc being separated from the other by 

 a layer of cloudy fluid (Fig. 146). The gel- 

 atin is not liquefied. The germ does not grow 

 on potato. On agar-agar or blood-serum the 

 growth is devoid of any characteristic. 



The organism is pathogenic for mice and 

 swine. The bacilli are found in all the 

 organs, especially the spleen and lungs. 



Many of the germs are enclosed by the leucocytes. 

 It is possible to produce temporary immunity by injecting 



the blood-serum of rabbits immunized with pure cultures of 



the bacillus. 



Bacillus of mouse 

 septicaemia ; gelatin 

 puncture ; culture 

 three and a half 

 days old. (Guen- 

 ther.) 



