Studies with a single mixed nutrient were made with but one food material, this being whole milk. In addition, two experiments were made in which the milk was combined with one other food material, and in a considerable number of experiments the metabolism was measured after a diet such as would be taken in one or more ordinary meals.

Milk

No other single food material contains the three important nutrients, protein, fat, and carbohydrate, in such relatively well-balanced proportions as whole milk does. Three calorimeter experiments and one respiration experiment were made to study the effect upon the metabolism of the ingestion of milk. Statistical data not included in the tables or in the discussion of the experiments are as follows:

H. R. D., 8h40m A. M. To 4h40m P. M., March 21, 1908. 59.2 Kilograms

During experiment sat very quietly, reading about four-fifths of time; very drowsy at 10 a. m. Urinated 6h50m a. m., 11h40m a. m., and 4h55m p. m.; defecated (after enema) about 7h20m a. m. Body-temperature: 36.95°, 36.69°, 36.71°, 36.71°, 36.69° C. Pulse rate, 63; respiration rate, 19.

A. L. L., 8h40m A. M. To 4h40m P. M., March 22, 1906. 68.3 Kilograms

Urinated 7h20m a. m. and 4h57m p. m. Sat very quietly reading; not sleepy except near end of experiment. Body-temperature: 36.72°, 36.65°, 36.70°, 36.64°, 36.53° C. Pulse rate, 61; respiration rate, 19.

A. H. M., 8h30m A. M. To 4h30m P. M., March 23, 1906. 67.0 Kilograms

Urinated 6h30m a. m., 12h40m p. m., 4h45m p. m. Read very little, and sat quiet in chair; drowsy, especially in afternoon. Body-temperature: 36.59°, 36.44°, 36.42°, 36.44°, 36.33° C. Pulse rate, 53; respiration rate, 16.

H. F. T., 10h21m a.m. to 2h45m p. m., July 14, 1911. 57.9 kilograms - Milk experiment on this day preceded by observations of the gaseous exchange 8 1/2 hours after ingestion of beefsteak. (See page 286.) Tired and restless in fifth period. Nitrogen in urine per hour 7 a. m. to 10h40m a. m., 0.69 gram; 10h40m a. m. to 2h20m p. m., 0.72 gram.

Calorimeter Experiments

In the calorimeter experiments with milk, a study was made of the influence of approximately 600 grams of whole milk, in which 19 per cent of the fuel value came from protein, 52 per cent from fat, and 29 per cent from carbohydrates. These experiments were carried out with three subjects on successive days with the Middletown respiration calorimeter. As was usual with these earlier experiments, the only basal values obtainable were determined several days or weeks before or after the food study and hence are not ideal for purposes of comparison. The observations were all made in 2-hour periods.

H. R. D., March 21, 1906

The data obtained following the ingestion of 599 grams of milk and 9 grams of lime-water, with a fuel value of 444 calories, are given in table 231. These show an increment in carbon-dioxide production in all of the periods, with but 1 gram in the last period. The values for oxygen consumption were irregular, but a positive increment for the total experiment was obtained of 4 grams. The greatest increment in heat production was in the first period, with variations above or below basal thereafter. The influence of this amount of milk upon the metabolism of the subject was therefore relatively slight. The urine was collected but once for the experiment, and showed an average excretion of 0.86 gram of nitrogen per 2 hours.

Table 231. - H. R. D., March 21, 1906. Sitting. (2-Hour Periods). Milk (Whole)

Amount, 599 grams;1 nitrogen, 3.17 grams; total energy, 471 cals.

Fuel value: Total, 444 cals.; from protein, 19 p. ct.; from fat, 52 p. ct.; from carbohydrates 29 p. ct.

Nitrogen in urine, 0.86 gram per 2 hours.2 Basal values (February 6 to April 20, 1906): CO2, 47 grams; O2. 42 grams; heat, 146 cals.

1Also 9 grams lime-water.

2Sample included amount for about 1 3/4 hours without food preceding experiment.

A. L. L., March 22, 1906

The details of the experiment are given in table 232. The subject drank 598 grams of milk, combined with 9 grams of lime-water, with a fuel value of 382 calories. In the experimental period of 8 hours, the total increment for carbon-dioxide production was 20 grams, for oxygen consumption 6 grams, and for heat production 59 calories. The only basal values available were those determined 12 and 15 days subsequent to the food experiment. Nevertheless it is evident that the increment with this subject was materially greater than with the subject of the preceding experiment.

Table 232. - A. L. L., March 22, 1906. Sitting. (2-Hour Periods). Milk (Whole)

Amount, 598 grams;1 nitrogen, 3.15 grams; total energy, 410 cals.

Fuel value: Total, 382 cals.; from protein, 19 p. ct.; from fat, 52 p. ct.; from carbohydrates, 29 p. ct.

Nitrogen in urine, 0.83 gram per 2 hours.1 Basal values (April 3 and 6, 1906): CO2, 47 grams; O2, 43 grams; heat, 145 cals.

1Also 9 grams lime-water.

2Sample included amount for about 1 1/4 hours without food preceding experiment.