The postganglionic sympathetic nerve fibers can regenerate. First, Tuckett,1in 1896, and later, Machida,2in 1929, demonstrated this clearly, with the fibers leaving the superior cervical ganglion for the eye. Observations on the return of vasomotor and sudomotor function after section and suture of a peripheral nerve, made in the experimental animal by Kilvington and Osborne,3in 1907, and on man by Head,4in 1920, and by Trotter and Davies,5in 1909, indicate that the postganglionic fibers are, indeed, among the fastest growing of the fiber components of such a nerve. Recently, however, a new method has become available by which the state of sympathetic function in surfaces relatively free from hair can be studied. By the determination of the presence or absence of action currents in the skin, either spontaneous waves in the electrical potential of the skin or the reflexly elicited galvanic skin