Of more than ordinary interest in connection with the problem of the cause of rickets is the immunity of the inhabitants of the West of Ireland (27) and of the Island of Lewis in the Hebrides (28). In the former place much land is unsuitable for agriculture and cattle and sheep raising are highly important industries. In fact there are few places in the world where the number of cattle in proportion to the population is greater than in Ireland. So far as the author's investigations have gone, everything points to the conclusion that wherever a region is hilly and unfit for agriculture, or where the soil is thin or poor and suited only for the grazing animals, fine physical development is characteristic of the people, and rickets is unknown or rare among the children. Where agriculture thrives and the growing of cereal grains and tubers is the most profitable form of agriculture, physical deterioration as shown by stunted growth, physical inferiority and defective development and caries of the teeth are likely to characterize the people both of the rural districts and of the cities, but especially the latter, because their diet is likely to be derived in larger proportion from cereal grains, tubers and muscle meats.