THE treatment of disease by sunlight is the newest of old things. It was systematically practised by Hippocrates, the Father of Medicine, and perhaps we need not trouble ourselves with questions of priority in our own times. At any rate, the first clinic for the heliotherapy of surgical tuberculosis was opened by Dr. A. Rollier at Leysin in 1903, and at last it would appear that his methods are to be followed throughout the world. Already in France and Italy the sun cure is practised, and I recorded lately in NATURE (March 2) the finding of many heliotherapeutic institutions on the Riviera, from Cannes to San Remo. The city of Lyons wisely sends its sick children to the Villa Santa Maria at Cannes, and the Italians have recently established the Istituto Elioterapico which I found outside San Remo a few weeks ago. In our own country we have Sir Henry Gauvain at the Treloar Hospital, Alton and Hayling Island, and Dr. Gordon Pugh, at Queen Mary's Hospital for Children at Carshalton. In the United States, Rollier is being followed at Perrysburg, near Buffalo.