DIPHTHERIA, 137 
3. Place the tube in an incubator at 37.5" C. for 
sixteen hours or longer. 
4. Examine the growth for the small grayish, 
slightly elevated diphtheria colonies. 
5. Prepare films from a suspected colony. 
6. Pass three times through the flame and stain 
in Loffler’s methylene-blue for one minute. 
Fic. 72,—Bacterium diphtheria, from culture upon blood- 
serum ; x 1000 (Frankel and Pfeiffer). 
7. Wash, dry, mount, and examine with the 7, 
inch oil-immersion lens. The characteristic diph- 
theria bacteria can easily be detected. 
8. Isolate the diphtheria organisms in pure cult- 
ure by inoculating tubes from a single colony 
which on examination proves to be diphtheria. If 
a single colony cannot be found, touch the needle 
