Acts especially upon the nerves of animal life and of special sense, and upon the fibrous and muscular tissues of the eye and the heart. It produces irritation of the nerves, resulting, in the motor sphere, in spasmodic movements of the facial muscles, subsultus tendinum, and even convulsions ; in the sentient nerves, to neuralgic pains, especially of the fifth pair and of the heart, which, together with the rheumatic condition of the eye and heart which it produces, is the most important action of the drug. Characteristic symptoms.