Water given off by the skin is classified as insensible and sensible perspiration. Under normal conditions about 600 to 700 c.c. is evaporated from the skin in twentyfour hours. The chief physiological significance of the perspiration is to assist in regulating the body temperature. The constituents of perspiration are very variable. The average values calculated from the examination of fourteen male specimens and ten female specimens are given below:— [Formula: see text] Examination of the figures obtained for the sweat shed by rheumatic subjects shows no marked divergence from those recorded for normal subjects. Lactic acid is stated to be present in relatively large amounts in sweat, but these results have not been confirmed. Moss (1923) demonstrated the importance of the loss of chloride which occurred during continued sweating. He showed that symptoms of water-poisoning occurred when men engaged in hard work in hot places drank water freely. Hancock, Whitehouse and Haldane (1930) point out that the percentage of chloride in sweat increases markedly with duration of sweating, and suggest that water poisoning is due to an alteration in the diffusion pressure of water in the body. The secretion is under control of the nervous system, and is normally excited through stimulation of the centres by warm blood. The sweat-glands are innervated by fibres of the sympathetic system. Adrenaline has, however, no action on the glands, while pilocarpine excites and atropine paralyses. Recent investigations suggest that acetyl-choline is liberated at the nerve-endings.

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A PRELIMINARY description of a vagus nerve smooth muscle preparation was recently given by one of us(l). This paper deals with further experiments using the same preparation. Little or no literature is available on the response of isolated smooth muscle to indirect stimulation, though Snyder and Light(2) have described a preparation in their experiments on the heat production of the urinary bladder of terrapin.Method. Rabbits, cats and dogs were used in these experiments. Cats and dogs were deprived of food for at least 12 hours, and then given a meal of meat juice 3 hours before the experiment. Rabbits were killed by a blow on the occiput, while cats and dogs were anaesthetized with ether. The stomach and cesophagus were removed from the animals and dissected under warm Ringer-Locke solution. The vagus nerve was identified on one side and dissected free from underlying tissue. The muscle supplied by the nerve was separated from the mucous membrane and removed as a strip. After some 20 minutes in warm solution the muscle was suspended in Ringer-Locke or Tyrode solution. Experiments were carried out at 370 C., bubbling and hydrogen-ion concentration being regulated.Optical methods were used to record the response of the muscle. A small galvanometer mirror was attached to a torsion spring and the movements of the beam of light recorded on bromide paper. Tracings were also made on smoked paper with light balanced levers. An induction coil was used, the nerve being placed on platinum electrodes outside the chamber. The frequency of the coil for tetanizing currents was 50 make and 50 break shocks per sec.Experinental results. Strips of cross-striated muscle supplied by the vagus nerve were removed from the rabbit's or dog's cesophagus and the upper region of the cat's cesophagus. The muscle usually responded by a quick twitch on stimulation of the nerve with a single break induc-

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