Studies with the Agar Cup-Plate Method: I. A Standardized Agar Cup-Plate Technique.

Official Circular 198 (Ruehle and Brewer, 1931) gives directions for performing the agar cup-plate test. However, in the limited literature dealing with the subject, no mention is made of the influence of varying the volume of agar, the amount of inoculum, the hydrogen ion concentration or other factors. In the course of other studies with the agar cup-plate method (Rose and Miller, 1939; Miller and Rose, 1939) it was learned that a slight modification in procedure caused a considerable difference in the experimental results. It therefore became necessary to study the influence of variations in technique in greater detail. The object was to standardize the method so that more constant data could be obtained. The present communication deals with this study.