On February 9, a nitrogen balance was attempted covering a period of six days, in which there was an exact comparison of the nitrogen income and output. In this balance period it will be observed that the total amount of nitrogen taken in for the six days was 53.108 grams, while the output of nitrogen through the kidneys amounted to 51.07 grams. The nitrogen excreted through the fæces, however, brought the total nitrogen output up to 58.83 grams, thus making a minus balance for the six days of 5.722 grams of nitrogen. During this period the average fuel value of the food per day was 2168 calories. The average daily output of metabolized nitrogen during the period was 8.5 grams, practically identical with the average daily excretion of nitrogen through the kidneys for the entire year, so far as determined. We have here a distinct minus balance, due either to an insufficient amount of proteid food, or an insufficient fuel value. _Tuesday, February 9, 1904._ Breakfast.—Oatmeal 237.5 grams, butter 10 grams, sugar 35 grams, milk 60 grams, coffee 210 grams. Lunch.—Macaroni 142 grams, cheese 10.5 grams, bread 71.5 grams, sweet potato 119.5 grams, milk 250 grams. Dinner.—Bread 80.7 grams, butter 20 grams, mashed potato 176 grams, string beans 77.5 grams, apple pie 82 grams, milk 250 grams. Food. Grams. Per cent Nitrogen. Total Nitrogen. Oatmeal 237.5 × 0.64 = 1.520 grams. Butter 10 + 20 = 30.0 × 0.088 = 0.026 Sugar 35.0 × 0.00 = 0.000 Milk 60 + 250 + 250 = 560.0 × 0.52 = 2.912 Coffee 210.0 × 0.10 = 0.210 Macaroni 142.0 × 0.87 = 1.235 Cheese 10.5 × 4.45 = 0.467 Bread 71.5 + 80.7 = 152.2 × 1.36 = 2.069 Sweet potato 119.5 × 0.28 = 0.334 Mashed potato 176.0 × 0.36 = 0.633 String beans 77.5 × 0.26 = 0.201 Apple pie 82.0 × 0.49 = 0.401 ------ Total nitrogen in food 10.008 grams. Total nitrogen in urine 8.460 Fuel value of the food 2094 calories. _Wednesday, February 10, 1904._ Breakfast.—Oatmeal 299 grams, butter 19 grams, cream 71 grams, sugar 41 grams, coffee 210 grams. Lunch.—Bread 79 grams, butter 11 grams, boiled potato 155.2 grams, milk 250 grams. Dinner.—Bread 56 grams, butter 12 grams, baked beans 100 grams, cranberry sauce 150 grams, sugar 21 grams, coffee 210 grams. Food. Grams. Per cent Nitrogen. Total Nitrogen.