Under normal conditions, that is, at room temp., etc., the hands and feet, like the face, show sharply-defined areas of low electrical skin resistance. On the hands, these patterns usually include the entire palmar surface up to the line which divides the dorsal and ventral parts of the hand. The skin of this area shows a resistance about 1/4 that of the skin of the surrounding areas. On the feet, the areas of low electrical skin resistance usually include the entire plantar surface and a small band along the side of the foot and over the toes. These areas become con- stricted in cold temps. and during sleep, and become enlarged in warm temps. and with exercise and excitement. When the patterns contract, the tips of the fingers and the toes are the last to show a low resistance. When they expand, the patterns first envelop all of the dorsal surface of the hands and feet and then move up the arms and legs, showing regular sock and glove patterns. The possible relationship of these areas to the distribution of sweat glands, blood vessels and hair was considered. The patterns do not conform to the distribution of any of the peripheral nerves or the sensory dermatomes. They may represent cortical or sub-cortical patterns of the distribution of sympathetic nerves to the extremities.