Editorial note — BACTERIOLOGICAL EXAMINATION.

J. (b) Synthetic Medium for the Methyl Red Test. To Make One Liter. Dissolve 7 grams Na2HPO4 (anhydrous) or 8.8 grams Na2HPO4.2H2O, 2 grams KHphthalate, 1 gram aspartic acid, and 4 grams dextrose in about 800 cc. of warm distilled water. When solution is complete, cool and make up to 1 liter at room temperature. Heat in an autoclave for 15 minutes after the pressure has reached 15 pounds, provided the total time of exposure to heat is not more than one-half hour. The hydrogen-ion concentration of the medium is fixed by the composition. It should be very close to PH 7.0, slightly red with phenol red. All materials should be recrystallized or if used from stock furnished by manufacturers, should be carefully examined. The di-sodium hydrogen phosphate may be used either as the anhydrous salt obtained by dessication in vacuo at 100° C. or else as the salt containing two molecules of water of crystallization. This is obtained by exposing the recrystallized Na2HPO4.12H2O for two weeks. Use 0.88 per cent. of Na2HPO4.2H2O.