Zephyranthes candida, Narcissus pseudonarcissus and Crinum asiaticum pollen were placed near their pistil parts respectively on agar cultural media (microslides) containing 10% sucrose and 100㎎/1 boric acid plus 1% agar with or without calcium and some other calcium-supporting inorganic salts. If fresh pistils (100% moisture) were used pollen grew toward their pistil parts, showing "positive" tropism. This was also true when combinations among three different species were made. Pollen tubes grew away from the pistils if they were dried (below 10% moisture), showing "negative" tropism. Pollen could not show sny tropic growth and thus grew at random of all directions if the pistil parts were incompletely dried (approximately 50% moisture). The similar tropic responses of pollen-tube growth with the three species could be demonstrated with either wet or dried tooth-pick segments. Calcium ions in the basic medium merely promated pollen-tube growth and so either"positive" or "negative" tropism became rather distinctive, but they were not tropically active. Pollen tubes grow toward pistil parts with more moisture content and seem to be hydrotropically sensitive. This was assumed due to the cohesive force existing in water molecules.