416 THE HEMORRHAGIC SEPTICEMIA GROUP 



in rats, for in the latter Bacillus pseudotuberculosis rodentium, Bacil- 

 lus tularense, and other organisms may be present, which produce 

 lesions superficially not unlike those of plague. 



Cultural Diagnosis. Prepare agar plates from the contents of 

 enlarged glands or other material incubate at 30 C. (or 37 C.), 

 and isolate colonies in pure culture. Blood, collected aseptically, 

 should be plated out on agar. From the pure colonies inoculate 3 

 per cent, salt agar and examine after twenty-four hours for involution 

 forms; make the "stalactite" test in broth containing .a few drops of 

 neutral oil. (The culture must be kept in an absolutely quiet environ- 

 ment to obtain stalactite growth.) This reaction is not absolutely 

 distinctive for other members of the Hemorrhagic Septicemia Group 

 may also develop in this manner. 



Animal Inoculation. A small amount of culture inoculated at the 

 root of the tail of a rat subcutaneously or intranasally in a guinea- 

 pig will cause death within three to five days with characteristic 

 lesions. The organism may be recovered from the internal organs. 

 If the material for inoculation be mixed with adventitious bacteria, 

 the cutaneous method of inoculation 1 of guinea-pigs will give positive 

 results and the organisms may be recovered in pure culture from the 

 internal organs postmortem. 



1 Albrecht and Ghon, loc. cit. 



