In 1 minute the pupils of the eyes were dilated and the respiration was laborious. " 2-1/2 do. vomiting and staggering. " 4 do. evacuations; the cries continued, the voice hoarse and unnatural. " 5 do. repeated attempts at vomiting. " 7 do. respiration somewhat improved. At this time a large drop was rubbed upon the tongue. In an instant the eyes were closed, the cries were stopped, and the breathing was suffocative and convulsed. In one minute the ears were in rapid convulsive motion, and, presently after, tremors and violent convulsions extended over the body and limbs. In three and an half minutes the animal fell upon the side senseless and breathless, and the heart had ceased to beat. Slight tremors of the voluntary muscles, particularly of the limbs, continued, more or less, for nineteen minutes after the animal was dead. Those of the right side were observed to be more and longer affected than those of the left. Half an hour after death the body was opened, and the stomach and intestines were found to be contracted and _firm_, as from a violent and permanent spasm of the muscular coat. The lungs were empty and collapsed. The left side of the heart, the aorta and its great branches were loaded with black blood. The right side of the heart and the two cavae contained some blood, but were not distended. The pulmonary artery contained only a small quantity of blood. The blood was every where fluid. EXPERIMENT 2. A cat was the subject of this experiment. The general effects were very much like those in the last, excepting, perhaps, that the oil operated with a little less energy. This cat was said to have lived for several years, in a room almost perpetually fumigated with tobacco smoke. The history of the animal employed in Experiment 1, was unknown. EXPERIMENT 3. Three drops of the oil of tobacco were rubbed upon the tongue of a full-sized, but young, cat. In an instant the pupils were dilated and the breathing convulsed; the animal leaped about as if distracted, and presently took two or three rapid turns in a small circle, then dropped upon the floor in frightful convulsions, and was dead in _two minutes_ and _forty-five_ seconds from the moment that the oil was put upon the tongue. EXPERIMENT 4.