Feb. 9 7.832 grams. 7.49 grams. 9.5 grams. 10 7.674 6.14 11 9.770 8.02 32.0 12 9.483 8.82 9.5 13 7.622 7.17 28.0 14 10.656 7.73 24.0 ------ ------ ------ 103.0 grams contain 6.52% N. 53.037 45.37 + 6.715 grams nitrogen. ------ ---------------------- 53.037 grams nitrogen. 52.085 grams nitrogen. Nitrogen balance for six days = +0.952 gram. Nitrogen balance per day = +0.158 gram. Average Intake. Calories per day 2068. Nitrogen per day 8.83 grams. On June 1, near the close of the experiment, a second nitrogen balance was attempted, with a view to seeing if under the existing conditions of life and activity it was possible to reduce the fuel value of the food, and at the same time diminish in still greater measure the quantity of proteid food taken. The results of this trial are seen in the accompanying tables, where for four days a careful comparison of output and intake is shown. It will be observed from these tables that the average fuel value of the food per day was reduced to 1785 calories, and that the average intake of nitrogen was restricted to 6.73 grams per day. The balance shown is a minus balance, although the deficiency per diem is not large. It is very obvious that both the nitrogen and fuel value of the food can be reduced considerably below the average maintained during the period of the first balance, but not to the degree attempted in the second balance, and secure nitrogen or body equilibrium. It will be noted in this last nitrogen balance, that the average daily output of nitrogen through the urine amounted to 6.46 grams, while the average nitrogen intake was 6.73 grams. The fuel value of the food, however, averaged only 1785 calories per day. It is quite evident, if the non-nitrogenous food had not been reduced quite so much, that a plus nitrogen balance would have been obtained. Still, it is obvious that under the conditions of life and activity, this subject needed to metabolize only about 40 grams of proteid per day, with the total fuel value of his food equal to about 2000 calories, in order to secure both body and nitrogen equilibrium. Here, again, we have an illustration of the possibility of physiological economy which shows itself in a reduction of the daily proteid food more than 50 per cent, with a reduction of the non-nitrogenous food fully 30 per cent, and with maintenance of health, strength and vigor equal, if not superior, to that which the subject has ever experienced. _Wednesday, June 1, 1904._ Breakfast.—Champagne wafer 21.5 grams, tea 146 grams, sugar 15 grams.