AGAR-AGAR 103 



medium of fine particles that are not removed by filtration. 

 Add .5 percent normal hydrochloric acid. 



h. Filter through absorbent cotton on a funnel previously wet 

 with boiling water. 



i. Tube and sterilize in autoclave for fifteen minutes at 110 C. 

 Litmus, or lacmoid, or neutral red may be added to the gela- 

 tine as an indicator. 



AGAR-AGAR. 



To make agar : 



a. Take 20 grams of powdered or chopped agar. 



b. Add to 500 c.c. of water, place in a can in autoclave and heat 

 to 120 C. Then cool. 



c. Add this to 500 c.c. of bouillon of double strength, making 

 1,000 c.c. 



d. Neutralize. 



e. Cool to 60 C. 



f. Add an egg to the mixture, stir. 



g. Boil till egg is coagulated thoroughly. 



h. Titrate and adjust to desired acidity as given under bouillon, 

 and while boiling hot, filter through absorbent cotton wet 

 with boiling water, 

 i. Run into tubes. Sterilize. Slope the tubes for twelve hours 



and store in dark place. 



To make glycerine agar add 6 percent of glycerine to the agar 

 before neutralizing. To make agar for tubercle bacilli, veal bouillon 

 must be employed, and glycerine must be added. 



Litmus Milk. 



Carefully skimmed milk, to which litmus has been added, is run 

 into tubes and sterilized. This is a valuable culture medium. It 

 is also a reagent. 



