5. Distribute in test-tubes, 10 cc. to each tube, or in larger
containers as desired.
6. Sterilize in the autoclav at 15 lbs. (120° C.) for 15 minutes after
the pressure reaches 15 lbs.
f. _Nutrient Agar. To Make One Liter._
1. Add 3 grams of beef extract, 5 grams of peptone and 12 grams of agar,
dried for one-half hour at 105° C. before weighing, to 1,000 cc. of
distilled water. Boil over a water bath until all agar is dissolved, and
then make up the loss by evaporation.
2. Cool to 45° C. in a cold water bath, then warm to 65° C. in the same
bath, without stirring.
3. Make up lost weight and adjust the reaction to a faint pink with
phenol red, or if the phenolphthalein titration is used, and the
reaction is not already between +0.5 and +1, adjust to +1.