The cutaneous respiration of the cat is about 0.54% of the pulmonary respiration. The O absorption in terms of absorption per unit of body surface is 31.4 cc. per sq. m. The exchange of gases through the skin under normal conditions is the result of wholly independent metabolic processes which are confined to the epidermis. The deeper layers of the skin are not involved. The skin exhibits an irreciprocal permeability to the passage through it of CO2 and O. There is reason to believe that the skin is impermeable to the outward diffusion of CO2 and to the inward diffusion of O; whereas it is freely permeable to CO2 and O when passing in the reverse directions.