56 BACTERIOLOGICAL ANALYSIS. 



(«) Liebig's meat extract . 3 to 4 grammes. 



Peptone .... 10 grammes. 



Salt 5 grammes. 



Water (distilled) ... 500 cc. 

 Boil up together for 15 minutes. • 



(b) Agar (prepared as above described) 15 grammes- 

 Distilled water . . . 500 cc. 



These are placed in a flask in the autoclave, and the 

 temperature run up to 134°C. 



Mix the two solutions, neutralize, cool to 60°0. add 

 the whites of two eggs, and proceed as before described- 

 Blood Serum. Either the serum which separates 

 from the clot or the fluids which are effused in Pleurisy 

 or Ascites, may be employed in the making of this 

 nutrient medium. It is one of the most difficult culture 

 materials to handle satisfactorily. Blood is collected at 

 the slaughter house, from cattle or sheep, in well stop- 

 pered sterile litre jars. The blood is collected after it 

 has run for some time from the cut vessels, as it lessens 

 the danger of contamination. The jars are then set on 

 ice for 24 to 48 hours, and the serum which collects is 

 syphoned off into sterile flasks, with a sterile pipette. 



Several culture media are prepared from this serum. 



(a) Loeffler's serum mixture. To 3 parts of the 

 serum add 1 part of 1% grape sugar broth. Run into 

 sterile test tubes and then place these tubes properly 

 slanted in the serum coagulator, and expose them for 

 2^ to 3 hours to a carefully regulated temperature of 

 from 90° to 95°C. This firmly sets the tubes. After- 



