The relation of tobacco to the physical welfare of man can only be fairly estimated by viewing the subject in its broadest aspect; by considering its effects upon the race as a whole rather than in individual cases; by taking into consideration economical and other social conditions that at first sight might be considered as having little relevancy to the medical side of the subject. But there can be no just consideration of the matter otherwise. The direct deleterious effects of the immoderate use of tobacco are readily observable; but the great bulk of the evil physical effects due to the moderate use of this plant are of an intermediate nature and not directly noticeable; nevertheless, they are real, and worthy of medical attention. The plainly marked results following the use of tobacco in relatively large amounts seem to be due to quick and extreme interference with nutrition, and a diminution of function of all kinds, which may be represented by anything from a slight decrease of appetite and digestive ability up to a complete loss of function of almost any important organ. Tobacco has stimulating as well narcotic properties, but as ordinarily used its stimulating effect appears to be slight as compared with its narcotic influence. In this respect it differs from alcohol, the use of which, owing to the usual method of introduction in large amounts through the stomach, produces directly, by stimulation, readily noticeable structural changes. But with tobacco the direct evil results are mostly of a functional character, and are more generally diffused, owing to the usual slow manner of introduction into the body. These two properties have an effect upon the body in moderate use as well as in immoderate use, the effect being simply in proportion to the quantity used, though the effects of moderate use may not be measurable by ordinary means. It is easy to see the effects of large amounts of tobacco in the stunted growth of adolescents; in functional cardiac disorders; in intellectual sluggishness, loss of memory, and color blindness; in loss of appetite, and other neuroses of motion, and marked blunting of various functions of sensation, and in degeneracy of descendants; but that lesser evils are produced must be proved mostly by inference, circumstantial collateral evidence, and analogy. The greater evils that are the outcome of a moderate use of tobacco are probably due to prolonged slight interference with nutrition, and consequent general decrease of vitality, which renders the individual more susceptible through indirect influence to the invasion of disease, and which lessens the capacity for productive effort.