Results of histo-chemical investigations on the diseased leaves attacked by the late-blight fungus and shoots inoculated with Phytophthora infestans were reported.
In the diseased leaves，the reaction of the tissues become gradually alkali side from sound part to poisining and necrotic part.
In the poisoning part, the activity of peroxydase, cytochromoxydase are enhanced, primary or secondary alcohol, aldehyde, amino acid, sugars and phenol etc. are distributed. Ammomium salts were increased but phosphate and nitrate were decreased.
In the brown part of the shoots inoculated with late-blight fungus the reaction of iron is positive but reaction of other heavy metals, e.g. Cu, Mn, etc., were uncertain. Potassium, nitrite and ammonium salts were increased but phosphate and nitrate salts were decreased. The reaction of aldehyde, phenol, (fatty or primary aromatic) amine and melanin were positive but reaction of ketone, methylketone,indole etc. were quite uncertain.
Rather large granule which can be stasined with Sudan III often appeared in the brown part or its neighboring part. The activities of cytochrmoxydase, perox dase, tyrosinase were enhanced.
The poisoning part and browned part show alkali reaction in reductive condition.
Cell membrane and granule, which is regarded as mitochondoria, appearing to various chemicals, and the correlation to the browning phenomena was suggested from these investigations.