RECORDS of sympathetic impulses in the cutaneous nerves of the frog have been published already [Adrian, 1930; Adrian, Cattell and Hoagland, 1931], and when these were made it was found that slow impulses, presumably sympathetic, could be detected in the cutaneous nerves of the cat when the hairs were erected as a result of asphyxia. The present work deals with the persistent or "tonic" discharges which are found in mammalian sympathetic nerves and are chiefly vaso-constrictor in effect. Records have been made from the cervical sympathetic and from various nerves in the abdomen such as the hypogastric and the nerves running from the celiac ganglia. For the cervical sympathetic we have used rabbits under urethane or chloralose and for the abdominal nerves, rabbits and cats.