The standards which have been adopted more or less generally throughout the civilized world, based primarily on the assumption that man instinctively and independently selects a diet that is best adapted to his individual needs, are open to grave suspicion. The view that the average food consumption of large numbers of individuals and communities must represent the true nutritive requirements of the people is equally untenable. Naturally, there is general recognition of the principle that food requirements are necessarily modified by a variety of circumstances, such as age, sex, body-weight, bodily activity, etc. It is obvious that the man of 140 pounds body-weight needs less proteid than the man of 170 pounds, and that the man who does a large amount of physical work demands a larger calorific value in his daily diet, _i. e._, more carbohydrate and fat, than the sedentary individual. The growing child, in proportion to his body-weight, plainly needs more proteid for the upbuilding of tissue, and there are many conditions of disease where special dietetic treatment is undoubtedly called for. Our contention, however, and one which we believe to be perfectly justifiable, is that the true food requirements of the body, under any conditions, cannot be ascertained with any degree of accuracy by observations of what people are in the habit of eating; that customs and habits are not a safe index of true physiological needs. On the contrary, we are inclined to the belief that direct physiological experimentation, covering a sufficient length of time and with an adequate number of individuals, will prove far more efficient in affording a true estimate of the quality and quantity of food best adapted for the maintenance of good health, strength, and vigor.