(1) The addition of adequate amount of trace elements such as B, Fe, Mn, Zn, Cu and Mo to the culture medium showed a remarkable promoting effect on germination of pollen grains of many kinds of plants and a definite suppressing effect on bursting of pollen grains in a hypotonic medium. Promoting effect of all trace elements together was greater than that of boron alone in case of Tradescantia reflexa, Hypericum chinense and Lilium longiflorum. Concentration of trace elements optimal to the germination was about 10 times greater than that in the case of water culture and it lay in the range of 0.5-1.5% basal trace element solution. (2) Effect of absence of particular trace element and comparative effect of boron compounds were examined. Sodium metaborate was more effective than boric acid inTradescantia reflexa andHypericum chinense. (3) Effect of the addition of asparagine to a solution of trace elements was observed with Tradescantia reflexa and Rhododendron lateritium. (4) Optimum concentration of trace elements in the culture media containing various kinds of sugars were determined with Tradescantia reflexa, Hypericum chinense, Lilium longiflorum and Lilium Maximowiczii. (5) Activity of peroxidase and of water uptake became greater by the addition of adequate amount of trace elements to the culture medium.