Table 49 gives a list of the food experiments, grouped according to the apparatus and diet used. It shows that 59 experiments were made with the respiration calorimeter in Middletown, 41 experiments with the chair calorimeter and 3 experiments with the bed calorimeter in Boston. In the experiments in which only the respiratory exchange was determined, 78 experiments were made with the universal respiration apparatus and 9 experiments with the Tissot apparatus. The research included, in all, 190 experiments, i. e., 15 chewing experiments, 11 experiments with water, 8 with coffee, 13 with beef tea, 65 with carbohydrates, 15 with a fat diet, 44 with a protein diet, and 19 with mixed nutrients.

The composition and fuel value of the food materials used in the experiments are shown in table 50. The values are, for the most part, directly determined or are computed from determined values. The composition of the mixed diets may be found in the section describing the experiments with mixed nutrients.1

1See table 235, p. 310.

Table 49. - Summary Of Experiments Following The Ingestion Of Food

1These include 6 heavy-breakfast and 2 heavy-supper experiments.

Statistical data for the subjects of the experiments following the ingestion of food are given in table 51. In all there were 39 male subjects, the average age for the period of experimenting ranging from 17 to 48 years. The large majority of the subjects were from 20 to 30 years of age. The average body-weight without clothing ranged from 48 to 83 kilograms. The greater number of the subjects had a body-weight between 55 and 65 kilograms.

The experiments with each class of nutrients are discussed in separate chapters in the following pages. In the tabulated results for the calorimeter experiments, the amount, nitrogen content, and total energy of the diet are given, also the fuel value, and the proportions of energy from the different nutrients. The basal values for the carbon-dioxide production, oxygen consumption, and heat production are likewise recorded, together with the basal nitrogen in the urine of the experimental day if this was obtained. Whenever the respiratory quotients are given for the food periods, the basal respiratory quotient, i. e., that obtained on the same day, is recorded for comparison. The period between the time the subject finished eating and the beginning of each experimental period after food is shown, also the total amount and the increase over the basal value for each of the three factors of metabolism (carbon-dioxide production, oxygen consumption, and heat production); the respiratory quotients are included in the tables only when significant. If available, the nitrogen in the urine excreted during the food periods is given, either as an average figure with the food data at the head of the table or for the individual periods in a separate column.

Table 50. - Percentage Composition Of Food Materials Used In Experiments.1

1For composition of mixed diets used in the research see table 235, p. 310.

2Atwater and Bryant, U. S. Dept. Agr., Office Exp. Stas. Bull. 28, 1906.

3Average value excluding that for A. W. W., May 25, 1907. 4Computed.

5Average value; when available actual determinations substituted for average and fuel values recomputed.

•Average of determinations for E. H. B., Apr. 8, 1907, and A. H. M., Apr. 29, 1907, with whom the actual determinations of protein were used and fuel values computed accordingly. For data regarding creatinine and creatine, see pp. 160 and 161. 7Average of determinations obtained in experiments other than those with E. H. B. and A. H. M. Actual determinations used when available and fuel values recomputed. 8Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, p. 203; in calculating protein from nitrogen the usual factor, 6.25, was used. 9Average value; determined values substituted when available.

10Also used for Prof. C. Nov. 20 and Nov. 22, 1909, in experiments with sucrose. 11Average of determinations obtained for A. L. L. and A. H. M., with whom the actual determinations of protein and energy were used. 12Average value, not including determinations used in first average for cream. 13Emery and Benedict, Am. Journ. Physiol., 1911, 28, p. 301. 14Also 7.5 p. ct. citric acid. Atwater and Bryant, loc. cit. 15Four analyses made elsewhere on samples of this product show on the average 39 p. ct. of maltose, 27 p. ct. of dextrose and 34 p. ct. of water. 16Assumed. 17Determined on sample for A. W. W., Apr. 25, 1907.

18Average of all values obtained for potato chips, excepting those included in first average; determined values substituted when available and fuel values recomputed.

Table 51. - Statistics Of Age, Height, And Weight Of Subjects Used In Experiments Following The Ingestion Of Food

1For years 1906 and 1907, respectively, because of marked difference in physical characteristics of subject.

The tables for the respiration experiments give the data for the diet, also the average basal values per minute for the gaseous exchange, the computed heat production, the respiration rate, and the pulse rate. The time of beginning each period of measurement after food and the results of the observations are shown, with the addition in some cases of the values for the inspiratory ventilation. While the increments in the metabolism have not been calculated, they are readily noted by a comparison of the average basal values with the data recorded for each period following the ingestion of food. The time when the food was taken is given in a footnote. In both the calorimeter and respiration experiments the subjects usually ate the food in 15 or 20 minutes; if longer than this was required, the time thus occupied is stated in a footnote.