In the first place, we want some precise definition of the quite vaguely understood word, "narcotic." What is a narcotic? _A narcotic is any poison which, when taken in sufficient quantities into the system, produces death by paralysis._ The tyro in physiology knows that death must start either from the lungs, the heart, or the nervous system. Now a narcotic is anything which, in due quantity, kills by killing the nervous system. When death is caused by too great a proportion of carbonic acid in the air, it begins at the lungs; but when it is caused by a dose of prussic acid, it begins at the medulla oblongata, the death of which causes the heart and lungs to stop acting. Prussic acid is, therefore, a narcotic; and so are strychnine, belladonna, aconite, nicotine, sulphuric ether, chloroform, alcohol, opium, thorn-apple, betel, hop, lettuce, tea, coffee, coca, hemp, chocolate, and many other substances. All these, taken in requisite doses, will kill by paralysis; and all of them, taken in lesser but considerable doses, will induce a state of the nerves known as narcosis, which is nothing more nor less than incipient paralysis. Every man who smokes tobacco, or drinks tea or coffee, until his hands are tremulous and his stomach-nerves slightly depressed, has just started on the road to paralysis: he may never travel farther on it, but he has at least turned the corner. Every man who drinks ale, wine, or spirit until his face is flushed and his forehead moist, has slightly paralyzed himself. Alcoholic drunkenness is paralysis. The mental and emotional excitement, falsely called exaltation, is due, not to stimulation, but to paralysis of the cerebrum. The unsteady gait and groping motion of the hands are due to paralysis of the cerebellum. The feverish pulse and irregular respiration are due to paralysis of the medulla oblongata. The flushed face and tremulous, distressed stomach, are due to paralysis of the sympathetic ganglia. And when a person is "dead-drunk," his inability to perform the ordinary reflex acts of locomotion and grasping is due in part to paralysis of the spinal centres. The coma, or so-called sleep of drunkenness, is perfectly distinct from true reparative sleep, being the result of serious paralysis of the cerebrum, and closely allied to delirium.[5] Now, what we have stated in detail concerning alcohol is also true of tobacco. A fatal dose of nicotine kills, just like prussic acid, by paralyzing the medulla, and thus stopping the heart's beating. The ordinary narcotic dose does not produce such notable effects as the dose of alcohol, because it is hardly possible to take enough of it. Excessive smoking does not make a man maudlin, but it causes restless wakefulness, which is a symptom of cerebral paralysis, and is liable, in rare cases, to end in coma. Its action on the cerebellum and spinal cord cannot be readily stated; but its effect on the medulla and sympathetic is most notable, being seen in depression