24 PEACTIOAL BACTERIOLOGY. 



DEMONSTRATION IX. 



Impression Specimens of Bacillus Anthracis — Pyogenic Micrococci — 

 Staining of Pus — Agar Plates. 



1. Impression specimens of Bacillus anthracis. 



(a) Examine the Anthrax plate cultures and when 

 colonies appear, gently press over a part showing them 

 a sterile cover glass. 



(6) Carefully raise the cover glass, dry by holding 

 high over the flame, and pass three times through the 

 flame. 



(c) Stain the film in Loeffler's methylene blue, or by 

 Gram's method. 



A stained impression of the colonies will be obtained. 



2. Prepare cover glass films from the agar or potato 

 cultures of Staphylococcus pyogenes aureus, albus, and 

 Bacillus pyocyaneus. 



Stain with anilin gentian violet, or Gram's method. 

 (B. pyocyaneus does not stain by Gram's method.) 



3. Prepare cover glass films from the agar and the 

 broth cultures of Streptococcus pyogenes. 



Stain with anilin gentian violet, or by Gram's 

 method. Contrast the appearances microscopically. 



4. Staining of pus from an abscess. 



(a) Make cover glass films by placing a drop of the 

 pus (obtained after the first gush, from an opened 



