The question of the effect of iodine manuring on the iodine content of plants has recently assumed considerable importance in view of the use of iodine as a cure and preventive of simple goitre. Whether the theory that goitre is due to deficiency of iodine be correct or not, it appears to be well established that small doses of iodine act both as a cure and a preventive of enlargements of the thyroid. It has therefore been suggested that a simple and effective method of general prophylaxis, in areas where goitre is at present endemic, might be found in increasing the iodine content of foodstuffs such as milk and eggs, by administration of iodine, and of plants by iodine manuring.