SUMMARY: A series of co‐operative experiments was conducted to compare the bacterial colony counts of soil obtained by workers in different laboratories, using soil extract agar and other media for the determinations. In the earlier experiments it was not possible to obtain a reasonable degree of reproducibility of results between laboratories even when the plating technique was carefully prescribed. By modification and more rigid standardization of the technique closer agreement was obtained in subsequent experiments. It is suggested that when co‐operative investigations are contemplated the participating laboratories should check their technique by the examination of ‘control’ soils. No evidence could be obtained to support the suggestion that higher colony counts are obtained by the use of soil extract media containing extract prepared from the same soil as the sample tested. The source appears to be immaterial so long as the soil for extract preparation is not of extreme type and has been well manured and cultivated.

SUMAlAItY : A standard method for the application of the laboratory pasteurization test for milk, and rinses and swabs of dairy equipment, is described. The interpretation of the thermoduric colony counts so obtained is discussed, and tentative advisory standards are suggested.THE increasing use of the laboratory pasteurization test applied to raw milk, and rinses and swabs of dairy utensils or milk plant, has created a demand for a standard technique for the determination of thermoduric colony counts. The writers have used the following method during the past five years and found that it gives reproducible results and is simple enough for routine purposes. They have based the technique on experimental findings (Clegg, Egdell, Thomas, McKenzie & Cuthbert, 1950).

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Summary: The flaming of taps before sampling caused no significant differences in the most probable numbers of coli‐aerogenes organisms or Bact. coli in water samples, or in the colony counts at 37 or 22°, though there was a tendency for the bacterial content to be lowered.

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