In the autumn of 1902 and in the early part of 1903, Mr. Fletcher spent several months with the writer, thereby giving an opportunity for studying his habits of life. For a period of thirteen days in January he was under constant observation in the writer’s laboratory, when it was found that the average daily amount of proteid metabolised was 41.25 grams, his body-weight (75 kilos) remaining practically constant. Later, a more thorough series of observations was made, involving a careful analysis of the daily diet, together with analysis of the excreta. For a period of six days the daily diet averaged 44.9 grams of proteid, 38.0 grams of fat, and 253 grams of carbohydrate, the total fuel value amounting to only 1606 large calories per day. The daily intake of nitrogen averaged 7.19 grams, while the daily output through the urine was 6.30 grams and in the fæces 0.6 gram; _i. e._, a daily intake of 7.19 grams of nitrogen, with a total output of 6.90 grams, showing a daily gain to the body of 0.29 gram of nitrogen, and this on a diet containing less than half the proteid required by the Voit standard and having only half the fuel value of the Voit diet. Further, it was found by careful and thorough tests made at the Yale Gymnasium that Mr. Fletcher, in spite of this comparatively low ration was in prime physical condition. In the words of Dr. Anderson, the Director of the Gymnasium, “the case is unusual, and I am surprised that Mr. Fletcher can do the work of trained athletes and not give marked evidences of over-exertion.... Mr. Fletcher performs this work with greater ease and with fewer noticeable bad results than any man of his age and condition I have ever worked with.”[30] It is not our purpose here to discuss how far these results are due to insalivation, or the more thorough mastication of food. The main point for us is that we have here a striking illustration of the establishment of nitrogen equilibrium on a low proteid diet and great physiological economy as shown by the low fuel value of the food consumed, coupled with remarkable physical strength and endurance. With data such as these before us we see the possible importance of a fuller and more exact knowledge of true dietary standards. We find here questions suggested, the answers to which are of primary importance in our understanding of the nutritive processes of the body; greater ease in the maintenance of health, increased power of resistance to disease germs, duration of life increased beyond the present average, greater physiological economy and greater efficiency, increased mental and physical vigor with less expenditure of energy on the part of the body. All these questions rise before us in connection with the possibility of maintaining equilibrium on a lowered intake of food, especially nitrogenous equilibrium, with a diminished consumption of proteid or albuminous food. Is it not possible that the accepted dietary standards are altogether too high?