Nitrum acts directly upon the spinal system, paralyzing the spinal cord and the heart, arresting the action of the latter in its diastole. It also produces an antiplastic and spoiliative effect upon the blood. It acts upon the kidneys, and upon the respiratory and alimentary mucous tracts as a decided irritant, in the former producing excessive action, diuresis, the solid constituents being also increased ; and in the latter irritation, leading to congestion and inflammation. Characteristic symptoms.