1. _Water._—Distilled water shall be used in the preparation of all
culture media and reagents.
2. _Meat Extract._—Liebig’s meat extract shall be used in place of meat
infusion. Other brands may be substituted for Liebig’s when comparative
tests have shown that they give equivalent results.
3. _Peptone._—Armour’s, Digestive Ferments Company’s, Fairchild’s, or
any other peptone which gives equivalent results may be used.