(1) Amylase activities in the germinating wheat seeds harvested from the plants grown under three different temperature rooms in the phytotron-adjusted to day-night temperature, 25-20, 20-15 and 15-13℃ respectively, were measured by a method modified from Ball's using two varieties belonging to winter and spring types. The results showed that the activities in seeds harvested from the cooler room were stronger than that from the warmer, especially in the case of winter type. (2) The same tendencies were also recognized in the case when three wheat varieties belonging to winter, spring and intermediate types were grown in the field condition in four different regions from north to south in Japan. (3) The physiological parallelism between the ecological and genetical variations in amylase activity conditioned by temperature differences during the growing period was detected in this study. (4) Amylase activity conditioned by modification due to the temperature condition increased in inverse proportion to February mean temperature, and the decrease of amylase activity per 1℃ of February mean temperatures was 0.04-0.05 cc in the three varieties used in this study. (5) Amylase activity conditioned by hereditary character also increased in inverse proportion to February mean temperature, and the decrease of amylase activity per 1℃ of February mean temperature was 0.09 cc, and it corresponded to twice that of modification.