In 1900 nutrition studies made for the purpose of solving the problems of economic animal production had developed the conception of the specific effects of different foods on the development of the body during growth, and for the performance of work or the production of milk, wool, etc. The skilled animal hus-bandryman was distinctly in advance of the human physiologist or the medical man in his knowledge of nutrition from the practical standpoint. Professor Atwater, who represented the most advanced thought of his time, wrote, in 1895, his "Chemistry and Economy of Food" (5), which clearly reflects his view that if we knew the composition of all the food-stuffs entering into the human diet, as determined by chemical analysis, their digestibility, and energy values, and the energy requirements of an individual at rest and when doing various kinds of work, we should have all the necessary data to enable us to plan a highly satisfactory nutritive regimen. The well-balanced diet was one in which the proportions among the several recognized nutrients corresponded with the standards adopted as the result of statistical studies of what people in different circumstances and in different localities were selecting for their food supply when guided by the appetite and by expenditure.