(1) For decimal system of group numbers see Table I. This will be found useful as a quick method of showing close relationships inside the genus, but is not a sufficient characterization of any organism. (2) The morphological characters shall be determined and described from growths obtained upon at least one solid medium (nutrient agar) and in at least one liquid medium (nutrient broth). Growths at 37° C. shall be in general not older than twenty-four to forty-eight hours, and growths at 20° C. not older than forty-eight to seventy-two hours. To secure uniformity in cultures, in all cases preliminary cultivation shall be practised as described in the revised Report of the Committee on Standard Methods of the Laboratory Section of the American Public Health Association, 1905. (3) The observation of cultural and biochemical features shall cover a period of at least fifteen days and frequently longer, and shall be made according to the revised Standard Methods above referred to. All media shall be made according to the same Standard Methods. (4) Gelatin stab cultures shall be held for six weeks to determine liquefaction. (5) Ammonia and indol tests shall be made at end of tenth day, nitrite tests at end of fifth day. (6) Titrate with N/20 NaOH, using phenolphthalein as an indicator; make titrations at same time from blank. The difference gives the amount of acid produced. The titration should be done after boiling to drive off any CO₂ present in the culture. (7) Generic nomenclature shall begin with the year 1872 (Cohn’s first important paper). Species nomenclature shall begin with the year 1880 (Koch’s discovery of the pour plate method for the separation of organisms). (8) Chromogenesis shall be recorded in standard color terms. TABLE I. A NUMERICAL SYSTEM OF RECORDING THE SALIENT CHARACTERS OF AN ORGANISM. (GROUP NUMBER.)