The rate at which CO2 and O pass through the skin is influenced (1), by a change in the temp. of the air next to the skin (2), by individual characteristics; and (3), by seasonal changes. The conception of Schierbeck that a critical temp. exists for CO2 elimination through the skin was not confirmed. The respiratory quotient of the skin varies from 1.04 to 1.94, with an average value of 1-37. The cutaneous respiration under normal conditions is approximately 1 % of the pulmonary respiration. When the CO2 tension of the air is higher than that of the blood, CO2 is absorbed; and when the O tension is lower than that of the blood, O is excreted. CO 3 excretion from exposed muscle tissue is about 14 times as rapid as from the skin.