II. In stimulant doses, by improving nutrition, it may cause a diminution of weight abnormally produced. III. In narcotic doses, by impairing nutrition, it may cause emaciation. IV. In narcotic doses, by impairing nutrition, it may aggravate obesity instead of relieving it.[24] [24] In this exposition we have assumed that the tobacco is smoked and the saliva retained. If the saliva be frequently ejected, the case is entirely altered. Habitual spitting incites the salivary glands to excessive secretion, thereby weakening the system to a surprising extent, and probably lowering nutrition. Many temperate smokers, who think themselves hurt by tobacco, are probably hurt only because, though in all other respects gentlemen, they will persist in the filthy habit of spitting. There is no excuse for the habit, for with very little practice the desire to get rid of the saliva entirely ceases, and is never again felt. In chewing, the saliva is so impregnated with the nicotinous constituents of the leaf, that the choice lies far more narrowly between spitting and narcosis. Of the two evils we shall not venture to say which is the least. In snuffing, too, the question is complicated by the acute local irritation caused by the contact of the stimulant with the nasal membranes. This, no doubt, has its medicinal virtues. But for a healthy man it is probable that smoking is the only rational, as it is certainly the only decent, way in which to use tobacco.