LABORATORY procedures for the in vitro testing of fungicidal agents were pioneered by Schamberg and Kolmer1 in 1922. Their method consisted of exposing a homogeneous fungus-spore suspension, obtained by agitation with glass beads, to varying dilutions of the test substances. Tests developed subsequently by McCrea,2 Emmons,3 and Hillegas and Camp4 also utilized microconidial or spore suspensions. However, in 1939, Burlingame and Reddish5 expressed the opinion that spore suspension methods failed to parallel clinical conditions and did not take into consideration the characteristic of penetrability of the fungicidal agent. Their method consisted of exposing mycelial masses cultivated on Sabouraud agar to fungicidal solutions for varying periods of time, transferring cork-borer-cut sections of the mat, first to aqueous broth for washing and thence to Sabouraud agar for growth. Subsequently, Golden and Oster6 showed that the aqueous-broth wash did not remove alcohol-soluble, water-insoluble fungicides from the mycelial mass. They suggested the use of 30% acetone in water