CHAPTER XVII 



THE ANTHRAX GROUP 



MEMBERS 



Bacillus anthracis. 



B. subtilis, including several varieties. 



Great caution is necessary in handling B. anthracis. 

 Inoculate agar-slants from stock-cultures of B. anthra- 

 cis and B. subtilis. 



1. Routine study. Observe particularly the colonies 

 formed on agar and gelatin plates, 



2 . Special study A . Make ' ' impression preparation ' ' 

 (Klatschprdparat) from a surface colony on a gelatin- 

 plate. 



Method 



a) Clean and flame a cover-slip carefully. 



b) Place on a colony of suitable size, and gently press 

 down, taking care not to press so hard as to disturb the 

 characteristic shape of the colony. 



c) Lift the cover-slip carefully with the forceps. 



d) Dry, fix, and stain with methylene-blue or by 

 Gram's method. 



e) Examine under low and high power (dry lens), 

 and sketch what you see. 



3. Special study B. Staining of spores. Read care- 

 fully the different methods of staining spores. Why are 

 special stains necessary ? 



Moeller's method: 



a) Prepare several (five or six) films in the usual 

 manner from 24-hour-old agar-cultures of B. anthracis 



(or B. subtilis). 



98 



