CHAPTER XV 



THE DIPHTHERIA GROUP 



Members — 



Bacillus diphtheriae. 

 B. pseudodiphthericus. 

 B. xerosis. 



Use great caution in handling members of this group. 

 Inoculate agar-slants from stock-cultures of B. 

 diphtheriae and B. pseudodiphthericus. 



1 . Routine study.— Sii&m. B. diphtheriae with LoefiSer's 

 methylene-blue instead of gentian- violet. The staining 

 may be facilitated by the application of mild heat. 

 Observe particularly the peculiar effects of the staining 

 process, and make accurate sketches of what yon see 

 under the microscope. 



2. Special study A. — Neisser's method of staining to 

 demonstrate the granules in the baciUi: 



a) Prepare two solutions. 



SOLUTION 1 



Methylene-blue i g. 



Dissolve in alcohol g(>% 20 c.c. 



Add distilled water 950 c.c. 



Glacial acetic acid 50 c.c. 



SOLUTION II 



Bismarck brown 2 g. 



Distilled water 1000 c.c. 



h) Prepare a film in the usual manner from a culture 



of B. diphtheriae on blood-serum (furnished). 



c) Stain in Solution I for 5 to 6 seconds. 



d) Wash in water. 



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