THE PREPARATION OF BLACK-LEG VACCINE 307 



EXERCISE 5. THE PREPARATION OF BLACK-LEG VAC- 

 CINE 



Apparatus. Sterile mortar and pestle; sterile cheese- 

 cloth; two sterile glass plates; sterile water; sterile homeo- 

 pathic vials. 



Culture. Diseased muscle of calf affected with black- 

 leg. 



Method. 1. Place a piece of diseased muscle from a 

 calf affected with black leg (this will be furnished by the 

 instructor) in a sterile mortar, add a small quantity of 

 water and triturate completely with a sterile pestle. 



2. Squeeze the pulp through a piece of sterile cheese 

 cloth, spread the filtrate in a thin layer over a sterile glass 

 plate or saucer and dry at a temperature of 35 to 37 C. 

 in an atmosphere free from contamination. 



3. Mix approximately one part by volume of the dried 

 virus with two parts of water, triturate until the mixture 

 is converted into a semi-solid homogeneous mass and spread 

 in a thin layer over a glass plate or saucer. 



4. Heat in an oven to a temperature of 100 to 104 C. 

 for a period of seven hours. 



5. One centigram of the attenuated virus mixed with a 

 small quantity of water is a dose for a calf. Place the 

 product in sterile vials, ten doses to the vial, place a cork 

 stopper in each vial and seal. 



REFERENCES 



NORGAARD, V. A., and MOHLER, J. R.: Black leg, its Nature, Cause 



and Prevention, B. A. I. Circular No. 31, revised (1911). 

 MARSHALL: Microbiology, pp. 472-473. 

 KOLMER: Infection, Immunity and Specific Therapy (1915) p. 655. 



