The third fact which became clear in connection with the examination of the dietary practices of man and animals, was that diets which were derived from miscellaneous sources such as cereal grains, legume seeds, tubers, fleshy roots, with or without meats, but supplemented with liberal amounts of milk, sufficed to maintain satisfactory growth and marked vigor. Animal husbandry experience afforded strong evidence of the excellence of milk as food for growing animals, but especially of its high value for supplementing other foods such as the cereals in pork production. It was recognized generally, that the two best methods for promoting growth in swine were, either to combine milk production with a creamery, so that the skim milk could be returned to the farm and fed to hogs as a supplement to corn, or to feed the grain raised on the farm to hogs which were supplied a good pasture. The explanation of the cause of success of either of these practices was not understood, but we now appreciate the unique significance of the value of the mineral content and the fat-soluble A content, as well as of the supplementary value of the proteins of the leaves of our best forage plants, and of milk, in making good the deficiencies of the grains in these factors. The great value of skim milk in pork production made it very desirable to find a substitute for milk in the rearing of calves, and much effort has been expended in several of the Agricultural Experiment Stations in America to find a calf feed which was derived from foods other than milk which would prove wholly satisfactory. The results of these efforts have supported the view that there is no effective substitute for milk.