抄録
1) Basal metabolism was measured on 9 male adults every month throughout one year or two in a room at uniform temperature. The metabolism undergoes seasonal changes, increasing progressively with getting cold and decreasing with getting warm. The average maximum range of this variation is 17.6% of the mean for the year in Kyoto, where the monthly mean atmospheric temperature shows a variation about 22.2°C. in a year.
2) The changes in basal motabolism lag behind those in environmental temperature. Consequently the metabolism is higher in the spring than in the fall, even when the environmental temperature is the same.
3) Monthly determinations of P. B. I. in serum were made on 4 subjects throughout one year, and similar seasonal variation to that in basal metabolism was found. The maximum content 7.9γ% was found in January and the minimum of 4.7 r% in August. There is a clear positive correlation between metabolism and P. B. I.
4) It was verified experimentally that both the basal metabolism and the concentration of serum P. B. I. can be reduced in parallel by changing the environmental temperature to a summer level (about 30°C.) from the winter cold (about 9°C.) and staying there over a week or so.
5) From these, it is concluded that the thyroid activity present adaptative changes to seasonal changes of environmental temperature, and thus the seasonal alteration of basal metabolism is provoked.
