It should be reiterated that there are two classes of food-stuffs, of peculiar value in human and animal nutrition. These tend strongly to correct the deficiencies in a cereal, legume seed, tuber and fleshy root diet, or one in which in addition to these muscle meats are included. These are milk and the leafy vegetables (11). These, the protective foods, should always play a prominent role in the nutrition of man. Eggs and the glandular organs of animals such as liver, kidney, etc., serve to correct partially the deficiencies of the type of diet derived solely or nearly so from vegetable foods functioning as storage tissues, but they cannot take the place of milk and the leafy vegetables because they are too poor in calcium. The observation of Steenbock that certain edible roots contain considerable amounts of fat-soluble A does not alter in a practical way the supplementary relationship between the two classes of foods discussed, for the protein and inorganic factors are not much improved by making combinations of any foods of the type of storage tissues.