Abstract
During the June of 1935, studies were made regarding the light intensity and the photosynthesis of Chara in Lake Asinoko, Hakone. Light intensity was determined by the amount of decomposition of K I under acid medium. The amount of photosynthesis was determined by oxygen production as measured by a WINKLER method being corraborated by pH determinations. The optimum depth for photosynthesis was between 1 and 6 meters on bright day and was at the surface at the evening. Exposure under too much light proved that the photosynthesis was almost ceased. The lower limit of Chara growth of this lake found to be 20 meters below the surface, which was roughly correlated to the compensation depth of it on the bright day (18 meters).
