456 BACTERIOLOGICAL ANALYSES 



2. If the resulting growth resembles that of the 

 streptococcus, make subcultivations upon nutrient agar. 



3 . Prepare subcultivations of any suspicious colonies 

 that appear, upon all the ordinary media, and study 

 carefully. 



If the streptococcus is successfully isolated, inocu- 

 late serum bouillon cultivations into the mouse, guinea- 

 pig, and rabbit, to determine its pathogenicity and 

 virulence. 



7. Staphylococcus Pyogenes Aureus. 



1. Examine carefully the growth upon the serial 

 blood serum cultivations prepared to isolate B. diph- 

 therias and the serial agar cultivations to isolate strep- 

 tococci after forty-eight hours' incubation. 



2. Pick off any suspicious orange coloured colonies, 

 plant on sloped agar, and incubate at 20 C. Observe 

 pigment formation. 



3 . Prepare subcultivations from any suspicious 

 growths upon all the ordinary media, study carefully 

 and investigate their pathogenicity. 



8. Micrococcus Melitensis. The milk from an animal 

 infected with M. melitensis usually contains the organ- 

 isms in large numbers and but few other bacteria. 



1. Spread several sets of surface plates upon nutrose 

 agar, each from one loopful of the deposit in tube D 1 

 orD 2 . 



2. Spread several sets of surface plates upon nutrose 

 agar, each from one drop of the original milk sample. 



3. Incubate aerobically at 37 C. and examine daily 

 up to the end of ten days. 



4. Pick off suspicious colonies, examine them micro- 

 scopically and subcultivate upon nutrose agar in tubes ; 

 upon glucose agar and in litmus milk. 



5. Test the subsequent growth against the serum of 

 an experimental animal inoculated against M. melitensis 

 to determine its agglutinability. 



