Abstract
1. In CuSO4-NaOH-Na3 citrate mixture, the moler ratio Cu/citrate of the Cu-citrate complex is 1:1 in strong alkaline solutions, while both complexes with molar ratios 1:1 and 1:2 coexist in less alkaline solutions.
2. In CuSO4-Ca(OH)2-glucose mixture, a Cu-glucose complex is formed, in which the molar ratio Cu/glucose is 1:1.
3. In the acidity, the activity of Cu++ in CuSO4-Na3 citrate mixture is exceedingly smaller than that in CuSO4-glucose mixture.
4. The following assumption as to the action of Bordeaux mixture has been suggested: under a strong alkaline condition as exists at the plant surface sprayed with the Bordeaux mixture, Cu forms a complex with glucose or similar substances, and goes into solution. As soon as the complex thus formded is absorbed in the cell, intracellular pH being between 5_??_7 it decomposes to liberate Cu++. It is pressumed that the Cu++ is biologically active.
