Abstract
(1) The secondary-growth of potato-tubers inducig artificially by changing the ehvironmental conditions were studies with water cultur, using "Danshaku" in 1948. (2) It is clealy evident from the results herein presented that the high temperature (40°C), light exposur, dryness and concentrated cultur solution are all causes of secondaiy-growth of potato-tubers. (3) It is suggested as the basic cause of secondary-growth may be due to some growth substance which is affecting by abnorml condition of environment.