1. Previously it has been shown by the author that free oxalic acid accumulates in the glucose peptone medium of wood brown-rot fungi, where as it is not the case in most of white-rot fungi. Now the author got the same results on the potato-glucose agar by 39 species of wood rot fungi. This fact is thought that this serves as a good reference to diagnose the form of wood rot of these species of fungi as well as BAVENDAMM's Reaction. This method is very easy but we take care of the time of culture when we test. 2. A brown-rot fungus Poria vaporaria and a white-rot fungus Coriolus veysicolor were cultured on the sawdust of the beech. The decayed sawdust by poria vaporaria was accumulated by free oxalic acid and the pH of the sawdust changed very low, but the decayed sawdust by Coriolus verusicolor was not accumulated by free oxalic acid but was accumulated by oxalate and pH change is negligible. 3. Poria vaporeria can assimilate well many species of hexose, xylose, starch, xylan, mannit, succinic acid, inulin, glycerine and accumulate oxalic acid from these carbon sources. Also this fungus can accumulate it from asparagine. 4. Later the author found a new enzyme which decomposes oxalic acid from white-rot fungus and studied these relationship.