428 PATHOGENIC BACTERIA. 



of bone. When further developed the colonies flow 

 together and give the plate a cloudy gray appearance. 

 The gelatin is not liquefied, but is gradually softened and 

 its evaporation thus aided. 



In gelatin puncture-cultures the growth is quite cha- 

 racteristic, and the tendency of the bacillus to grow 

 anerobically is well shown (Fig. 119). The develop- 



FlG. 119. Bacillus of mouse-septicemia: gelatin puncture-culture three and a 

 half days old (Gunther). 



ment takes place all along the line of puncture, but is 

 more marked below than at the surface. The growth 

 takes place in a peculiar form, resembling superimposed 

 disks, each disk separate from its neighbors and consist- 

 ing of an area of clouded grayish gelatin reaching almost 

 to the walls of the tube. This growth develops slowly, 

 and causes a softening rather than an actual liquefaction 

 of the gelatin. 



Upon agar-agar and blood-serum a very delicate, trans- 

 parent grayish line develops along the path of the needle. 

 It does not grow upon potato. 



The bacillus grows at the room temperature, but much 

 better at the temperature of the incubator. 



The disease affects quite a variety of animals, notably 

 hogs, rabbits, mice, white rats, pigeons, and sparrows. 



