VACCINE-THERAPY 37 



2. On blood-agar small distinct colonies develop, with a 

 clear halo round them. 



3. On gelatin small white granular colonies form. 

 Gelatin is not liquefied. In stab culture distinct colonies 

 form along the track of the needle. 



4. On potato growth very sparing. 

 Staining. — Carbol-methylene blue and Gram's. 

 Microscopical Appearances. — Note characteristic long or 



short chain formations. 



Facultative Anaerobic. — Minimum temperature, 10° C; 

 optimum, 35° C. Growth also takes place at room 

 temperature. 



Pneumococci. 



Biological Characters. — 1. In broth difficult to grow, 

 and present nothing characteristic. 



2. On gelatin growth seldom takes place. 



3. On blood-agar small colonies develop, the trans- 

 parent medium becoming a dirty brown. 



Staining. — Carbol-methylene blue for original specimen ; 

 Gram's stain for cultivated specimen ; and also stain 

 capsule with a capsule stain. 



Microscopical Appearances. — The cocci are small, lanceo- 

 late in shape, and arranged in pairs. If further proof is 

 required, inoculate a rabbit, make a film of heart's blood, 

 and note capsule by capsular stain. 



Aerobic. — Minimum temperature, 20° C; optimum, 37° C.; 

 maximum, 40° C. 



Micrococcus Tetragenus. 



Biological Characters. — 1. In gelatin stab a thick 

 growth takes place, and a thick white disc forms on the 

 surface. On gelatin plates white round colonies form. 



2. On agar at room temperature moist white colonies 

 appear. 



3. On potato a thick, irregular slimy patch appears at 

 room temperature. 



