It gradually became the custom in Agricultural Experiment Stations to compare the effects of certain combinations of foods on the growth of young animals, and on milk production in cows. These experiments showed plainly that all rations of similar chemical composition are not alike in their physiological effects. In no instance was it possible, however, because of lack of knowledge of the several factors which enter into the normal diet, and because of the faulty planning and conduct of many of the experiments, to interpret the nature of the causes which determined their outcome. These belonged to the type of immediate utility experiment and were fostered by agricultural experiment stations because of their practical nature. They were of very great economic value since they showed clearly that certain combinations of foods were either poor, good or excellent for the nutrition of animals. The experiments were not, because of the nature of the food-stuffs employed, and because of the simple mixtures which were monotonously fed to the animals, of such a nature as to make possible deductions applicable to problems of human nutrition. Much of this experimental work was done by men with little scientific training. The experiments were therefore very poorly controlled with the result that much confusion prevailed. Instances were not infrequent where the title of a paper would lead one to believe that the experiments were designed to determine the efficiency with which a certain protein-rich concentrate supplements each of several cereal foods in the nutrition of growing swine, but a careful inspection would show that the ration described was fed to animals allowed to run on a pasture, and eating freely of a forage plant, or given such a skim milk supply as the dairy department afforded. But no account was taken of these factors in the interpretation of the results.