Physiologically we know that one of the special functions of the sympathetic nervous system is to control the tone of non-striate muscular tissue, and that we have filaments distributed from the sympathetic system in the muscular wall of every blood vessel, duct and organ throughout the body. We also know that the sympathetic is the accelerator nerve of the heart, being opposed in its action by the vagus which, is inhibitory; further, that the vagus is constant in its brake-like action, while the sympathetic only acts when stimulated either directly or reflexly. While the vagus is inhibitory to the heart it is motor to the lungs. Nerve force is not generated in the sympathetic system; the cerebro-spinal nerve force is conveyed to the ganglia by the rami communicantes and in the ganglia is transformed into sympathetic nerve force. We might compare the ganglia to electrical transformers. Such being the case it is not difficult to see that if the superior cervical ganglion receives the nerve-force for transformation from the upper four cervical nerves and we can prevent, or lessen, the passage of nerve-force from the spinal cord through those nerves to the ganglion, that we will, to a corresponding degree, lessen the amount of sympathetic nerve-force transformed in the ganglion and transmitted from it by its branches. STIMULATION OR INHIBITION. We can produce stimulation or inhibition of a nerve at will; press suddenly and with a little violence upon the ulnar nerve where it lies in relation with the internal condyle of the humerus and we will find a manifestation of its physiological action, evidenced by a sense of pain in the ulnar and radial sides of the fifth finger and the ulnar side of the fourth, together with contraction of the muscles supplied by that nerve. But if our pressure be less intense and more prolonged we will inhibit the nerve and produce a sense of numbness in the same area together with temporary loss of muscular control.