Reactions to cold’ WYNDHAM,~. H., C.G. WILLIAMS,AND H. LOOTS.

very fat and an average man were exposed for 2-hr periods on three different occasions at each of the air temperatures of 27, 20, 15, 10, and 5 C. Measurements were made of metabolic rates and skin and rectal temperatures. In these ranges of air tempera-tures, the average skin temperature of the fat man was lower than that of the average man. Heat conductances of the average man were twice those of the fat man. A sharp increase in metabolism occurred when the average skin temperature fell below 30 C in the average man and below 25 C in the fat man. This suggests that the latter became habituated to a lower average skin temperature. Heat conductances of both men fell sharply to minimum values as the average skin temperatures fell to 27 C. These results suggest that, in cold conditions, vasoconstriction of peripheral blood vessels is directly relate