ALTHOUGH the pig has well-developed structures in the skin which conform morphologically with apocrine sweat glands, the animal does not appear to sweat. Measurements made by Moritz and Henriques1 and Ingram2 showed that at temperatures below the critical temperature, cutaneous water-loss over the general body surface, but excluding the snout, is similar to that in man and other animals. At high environment temperatures, however, even when body temperature is elevated, water-loss from pig skin is only of the order of 30 g/m2 h and can be accounted for by the increased vapour pressure gradient consequent on the increase in skin temperature which occurs after vaso-dilatation. Confirmation of a low evaporative heat loss also derives from observation made on the new-born pig by Mount3, who estimated that the increased evaporative loss at high ambient temperatures could be accounted for by losses from the respiratory tract alone.