Direct sunlight—I speak, of course, from the point of view of medicine—is a powerful agency. That as a therapeutic instrument it is powerful for good is now widely known. That it is equally or in even a greater degree powerful for harm is not, there is reason to think, so generally understood. It is my chief purpose in this paper to insist on the grave dangers involved in heliotherapy, as it is applied to tuberculosis, especially to pulmonary tuberculosis, and to urge that it be prescribed and administered with the greatest caution.
For much of the current abuse of heliotherapy we have as physicians no direct responsibility. The idea that sunlight will cure tuberculosis is an idea admirably adapted to win popular acceptance, since it fits in so perfectly with well known facts, and is in itself so immensely attractive. Nearly everybody has heard of the idea, or known some