Like many other substances employed in medicine, radium, as well as possessing extremely useful properties when rightly applied, may produce dangerous toxic effects (cf. Rolleston, and others). The first harmful consequences to be observed were burns, affecting the skin not only of the patient, but also of those who administered the treatment or were otherwise engaged with radium. Besides the immediate lesion, which was generally of long duration, there appeared to be involved a risk of subsequent malignant change. Other unfortunate consequences of the external but prolonged and less intense action of radium are of a more general nature. They are principally weakness, changes in the bone-marrow and the blood-system—resulting in serious and even fatal aplastic anemia, leukopenia, and rarely leukemia—sterility, and fibrosis of the parenchymatous organs. The cases of occupational poisoning among watch dial painters, investigated and reported in America since 1924 by Blum, Hoffman, and above all by Martland and his co-workers, called attention to a new form of radium intoxication, differing in principle from the forms mentioned above.