Growth rate and hydrocarbon contents of Botryococcus braunii strain Showa were measured under temperature variation in one day. While the strain cannot grow at the constant temperature of 35°C, it can grow in the temperature variation of 35°C in a light period and 28°C in a dark period, or in that of 28°C in a light period and 35°C in a dark period. This indicates that sufficient temperature fall in the nighttime enables the strain to grow under outdoor condition if the temperature rises to 35°C in the daytime
