In the experiments on the 8-hour plan in Boston, both the chair calorimeter and the bed calorimeter were used for measuring the metabolism. In the chair calorimeter, which was the first calorimeter constructed in the Nutrition Laboratory, the subject remained comfortably seated in an arm chair throughout an experiment. The total volume of the air in the chamber was approximately 1,400 liters; the air space and body activity were therefore much more restricted than in the Middletown calorimeter, in which the chamber had a volume of approximately 5,000 liters, affording opportunity for considerable movement. In the chair calorimeter the water bottles and urine bottles were conveniently placed near the subject and it was unnecessary to rise from the chair for their use; there was, however, some minor muscular activity, such as the motions accompanying the reading of a book, and similar movements. The actual activity in the chair-calorimeter experiments was very considerably less than that in the calorimeter experiments in Middletown, save when the latter experiments were made during the periods from 11 p. m. to 7 a. m. with the subject asleep in bed.

The chamber of the bed calorimeter was even smaller than that of the chair calorimeter, being approximately 950 liters in volume. The subject lay upon a cot and it was impossible for him to sit up or to move very much except to turn the body from side to side. The food aperture was never opened during an experiment. Occasionally the subject drank water, and urine collections were sometimes made. During the greater part of the time the subject read quietly or slept. The results of the experiments with the bed calorimeter may thus consistently be used as evidence of an approximate basal metabolism - i. e., the minimum metabolism with nearly complete muscular repose and in the post-absorptive condition.

All of the Boston experiments were made with the subject in the post-absorptive condition (12 hours after food). Furthermore, it was possible in these experiments to obtain a graphic record of the muscular activity by means of a pneumograph fastened around either the chest or the thighs and connected with a tambour outside the chamber. Inasmuch as the air volume of the two calorimeters used in Boston was smaller than that of the Middletown apparatus and the subject was considerably quieter, the measurements could be made with a higher degree of accuracy, especially as the activity was controlled by means of the graphic record. It was thus possible to subdivide the experiment into shorter periods and to obtain values per hour or per three-quarters of an hour instead of for 2 hours, as with the Middletown experiments.

While the duration of the Boston experiments was approximately the same as that of the Middletown experiments considered in this section, the general plan was changed in that the basal metabolism was first determined for a number of periods, then the food was given, and the experiment was continued for the remainder of the 8 hours. The basal metabolism and the metabolism after food were thus determined on the same day in continuous measurements. This plan was followed with nearly all of the food materials studied except beefsteak.

Certain of the experiments were continued for periods longer than 8 hours in order to obtain further information as to the probable variation from hour to hour. In many instances observations were made with the same subject at intervals for many months or even years; a hint could thus be obtained as to the possibility of seasonal or yearly variations.

The first extended experiment in which the chair calorimeter was used was that made with J. R., December 3, 1908, although this apparatus had been tested in shorter experiments prior to this date. The results of this experiment, together with those of five other experiments with the same subject, are given in table 29. In this and the succeeding tables, the day is divided into hour periods, the results obtained in the individual periods being placed in the table according to the time the observations were made. Average values are also given both for the experimental periods and for the values obtained in the individual periods in all of the experiments. In considering the latter averages, it should be borne in mind that some of the individual values were determined several months or years apart.

Table 29. - Basal Metabolism Of J. R. At Different Times Of Day In Chair-Calorimeter Experiments. Boston

(Values per hour).

1The beginning of the "First hour" was for this subject approximately between 8h30m a. m. and 9h45m a. m. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature.

The carbon-dioxide production with this subject was remarkably constant, as shown by the figures in both sets of averages. Individual variations may be noted, however, the values being in two cases as high as 28.5 grams per hour and in several instances as low as 25.5 grams. On the whole, the agreement shows rather remarkable uniformity, not only from month to month but from hour to hour. The same uniformity is, in general, shown in the averages for the oxygen consumption. The range in the individual values is from 20 grams to 24.5 grams. Considerable variation appears in the values for the heat production. Thus in the fourth hour a value as high as 89 calories was found, while in another instance we have a value as low as 71 calories. When the average values alone are considered, the variations from hour to hour are found to be quite small, with the single exception of the average for the fourth hour. In general, this subject produced 77 calories of heat per hour.

Table 30. - Basel Metabolism Of F. M. M. At Different Times Of Day In Chair-Calorimeter Experiments

Boston.(Values per hour).

1The beginning of the " First hour" was for this subject approximately between 8h30m a. m. and 9h30m a. m. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature.