Abstract
The principle of logarithmic dilution resulting from passage of a diluent through a solution in a closed system is used in an apparatus for obtaining samples of soil suspension of known dilution for microbial assay. The device consists of a 14-ml glass chamber containing a magnetic agitator. As sterile water flows through the chamber in which a soil sample has been placed, the dilution of the sample in the effluent depends upon the amount of water used. Samples of effluent can thus be collected for replicated plating at any desired dilution, or aliquots can be plated directly at dilution intervals selected so that some portion of the series will yield plates with the optimum number of colonies for counting. The method is simple and timesaving and should compare favorably in accuracy with conventional procedures.

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