38 PRACTICAL BACTERIOLOGY. 



DEMONSTRATION XIV. 



Diphtheria Bacillus — Cultures of Spirilla of Asiatic Cholera, of 

 Metchnikof, and of Finkler and Prior — Inoculation 

 of Animals with Diphtheria Bacilli — Diph- 

 theria Toxin — Antitoxin. 



1. Make cover glass preparations from the colonies 

 of Bacillus diphtherige on the blood serum and glycerine 

 agar tubes. 



Stain with Loeffler's methylene blue, and also by 

 Gram's method. Note the variable morphology of the 

 bacilli, and the differences between the growth on the 

 different culture media. 



Clinically, cultures are made on blood serum or 

 glycerine agar, from suspected throats, and after incu- 

 bation for 16 to 20 hours, the tubes are examined. The 

 material is best removed from the throat by a small 

 swab, prepared by wrapping a fragment of absorbent 

 cotton about the end of a fairly rigid wire, which is 

 then placed in a plugged test tube and sterilized in the 

 hot air sterilizer. The swab is placed against the mem- 

 brane, and firmly pressed upon it with a slight twirling 

 motion, taking care not to touch other parts. The 

 swab is then lightly rubbed over one or more culture 

 tubes. Immediate staining and microscopic examina- 

 tion might be made of the material on the swab, but 

 owing to the presence of numerous saphrophytic bac- 

 teria, and of bacteria which somewhat closely resemble 

 Diphtheria bacilli in morphology, it is best to depend 

 on cultural examination. 



