Arsenic has a specific action on almost every organ, tissue, and secretion of the body. It acts directly upon the blood composition, upon the tissues, and upon the nervous system. The condition produced is one of asthenia, which characterizes the entire pathogenesis, and exhaustion of vital power, producing symptoms of impeded functional activity amounting in some cases to positive paralysis. This exhaustion, giving rise to lassitude, prostration, weakness, etc., is so peculiar to Arsenic , that it becomes at all times its most characteristic and important action, not resulting in all cases, as might be supposed, from organic destruction, but being present as a "sudden and complete sinking of the forces," due to functional causes alone. Of the tissues of the body the mucous membranes are most powerfully affected, producing irritation, inflammation, and ulceration, while upon the serous membranes and upon the skin is produced its peculiar irritated and inflamed condition ; in the former giving rise to copious effusions, in the latter to squamous and vesicular eruptions. The leading feature of this remedy is the nervous restlessness, with rapid emaciation and peculiar thirst. Characteristic symptoms.