DIPHTHERIA GROUP 95 



e) Counterstain with Solution II for 10-15 seconds. 

 /) Wash in water, examine in water, dry, and mount 

 in balsam. 



3. Special study B. Test for acid formation in a 

 culture, one week old, in neutral glucose-broth by addi- 

 tion of a few drops of litmus-solution. 



4. Special study C. Cultivation of B. diphtheriae 

 on eggs. (Method of Wyatt Johnston). 



NOTE. This method is recommended as an emergency cul- 

 ture test, the egg taking the place of Loeffler's blood-serum. 



a) Sterilize over the flame a small empty pot of meat- 

 extract, or any other vessel of suitable size. 



b) Carefully break with sterile forceps the shell of 

 a hard-boiled egg at the blunt end, taking care not to 

 rupture the membrane lining the shell. 



c) Flame the exposed part, and carefully free the 

 coagulated albumen from any membrane. 



d) Inoculate by gently rubbing some culture or throat 

 swab on the exposed egg-albumen. 



e) Invert and set in the sterilized pot. 

 /) Place in the thermostat, and 



g) Observe the appearance and make a stained 

 preparation after 24 hours. 



5. Special study D. Study of B. xerosis. Obtain 

 mucus from inner angle of the eyelids by stroking 

 with a platinum loop. Make two film preparations, 

 stain one by Gram's method and the other with methy- 

 lene-blue. Try culture on slant-agar and if impure, 

 plate out. Wherein does B. xerosis differ from the 

 other members of the group ? 



6. Special study E. 



