The 8-hour plan was used successfully in a large number of experiments at Wesleyan University in which the basal metabolism was studied for approximately this period on one day and on a subsequent day the metabolism after the ingestion of food was found for a corresponding period. The increment due to the food was then determined by comparing the results obtained. Uniformity in the degree of muscular repose was even more important in these shorter experiments than it was in the 24-hour experiments, and it was necessary to reduce the muscular activity to a minimum so far as possible.

The results of the experiments are given in tables 23 to 26. These tables show the experimental day divided into 2-hour periods, the data for the individual periods being placed according to the time the observations were made. The experiments usually began about 9 a. m., and the values in the "first period" commonly represent the values obtained approximately in the period between 9 a. m. and 11 a. m. Averages are given for each period and also for each experimental day. The carbon-dioxide production and oxygen consumption are shown in two significant figures and the heat production in three significant figures. The weighings of the carbon-dioxide are accurate to the tenth of a gram, but as there is always an uncertainty in determining the residual amount of carbon dioxide in a chamber of so large a volume as that of the Middletown calorimeter (approximately 5,000 liters), it seems permissible to record the results only to the nearest gram.

Table 23. - Based Metabolism Of A. L. L. At Different Times Of Day In Calorimeter Experiments, Subject In Sitting Position. Middletown

(Values per 2 hours).

1The beginning of the "First two hours" was for this subject between 7h45m a. m. and 10 a. m. 2Heat eliminated corrected for change in body-weight, but not for change in body-temperature.

With at least three of our subjects, A. L. L., A. H. M., and H. R. D., five or more basal values were obtained. (See tables 23, 24, and 25.) With both A. L. L. and A. H. M., difficulty was experienced in finding an average value, since with both subjects there appeared to be a distinct variation in the metabolism as measured at different times. For example, with A. L. L., the basal values determined from February 7 to April 6,1906, inclusive, were on an entirely different level from those found a year later. This is shown not only in the carbon-dioxide production, but also in the oxygen consumption and heat production.

Table 24. - Basal Metabolism Of A. H. M. At Different Times Of Day In Calorimeter Experiments, Subject In Sitting Position. Middletown

(Values per 2 hours).

1The beginning of the" First two hours" was for this subject between 9 a. m. and 9h 30™ a.m.

Hence the values for 1906 and 1907 are averaged separately. The average carbon-dioxide production per two hours for A. L. L. during the spring of 1906 was 47 grams; a year later the average of two experiments showed 53 grams. Similar variations were observed in the oxygen consumption, the average value for 1906 being 42 grams, while that for 1907 was 46 grams. The average heat production was 148 calories in 1906 and 165 calories in 1907.

Table 25. - Basal Metabolism Of H. R. D. At Different Time* Of Day In Calorimeter Experiments, Subject In Sitting Position. Middletown

(Values per 2 hours).

1The beginning of the "First two hours" was for this subject approximately between 8h30m a. m. and 9h45m a. m. 2Calculated to 2-hour basis; measured in period of 1 1/2 hours.

With the subject A. H. M. the basal metabolism determined on 2 days in the middle of February 1906 showed a distinctly lower value than the basal metabolism determined in the fall of 1906 and spring of 1907. Thus, the average carbon-dioxide production for February 1906 was 45 grams, the oxygen consumption was 40 grams, and the heat production was 142 calories, while the average values for the three experiments in the period from November 22, 1906, to March 9, 1907, was 51 grams for the carbon-dioxide production, 45 grams for the oxygen consumption, and 162 calories for the heat production. It is thus clear that with these two subjects we have a variation of at least 10 per cent, as shown by these duplicate experiments.

With both subjects there was an increase in weight between the two groups of experiments. With A. L. L. the weight in 1906 averaged 67 kilograms and in 1907 it averaged 73.4 kilograms, this increment in weight being approximately proportional to the increase noted in the metabolism. With A. H. M. the weight increased from 63.8 kilograms to 66.2 kilograms; this slight increase was by no means proportional to the increase in the metabolism. Although the values for the metabolism have not been presented on the basis of per kilogram of body-weight or per square meter of body-surface, it is obvious that with this latter subject the metabolic level was distinctly higher in the second group of experiments than in the first group. Accordingly, in determining the increment in the metabolism with food, it is impossible to use an average of these basal values for comparison and we must resort to a selection of data from the experiments made nearest in point of time to the food experiments.

A general examination of tables 23, 24, and 25 shows that there is a distinct tendency for the 2-hour values to diminish as the day proceeds. Not infrequently the value for the first period of the day is somewhat higher than the others. Inasmuch as nearly all of our experiments were planned on the four 2-hour period basis, this point demands special consideration. The general picture for the two subjects A. L. L. and A. H. M. (see tables 23 and 24) shows a definite though slight tendency for the metabolism to decrease as the day progresses, this being especially noticeable in the fifth and sixth periods. On the other hand, the average carbon-dioxide values for H. R. D. (table 25) are constant, while the oxygen values show, if anything, a slight increase; the values for the heat production are irregular. It should be remembered, however, that in several instances, and particularly with H. R. D., the average values for the later periods are not derived from values obtained on the same day as the averages for the preceding periods, and hence they do not represent consecutive 2-hour periods in all instances. Furthermore, while there are variations in individual periods, it is the average of all these values that is being discussed, and these averages indicate truthfully the general trend of the metabolism. The values for the subjects H. C. K, Dr. R., E. H. B., A. W. W., and H. B. W. (see table 26) usually show more constancy in the first four periods of the day, although in a number of cases those for the fourth period are high, especially for the heat production.