In the calorimeter experiments no attempt was made to apportion the increment from period to period and study the time relations to find if there were a "peak" effect. This was possible only with short-period experiments, such as could be made with a respiration apparatus. Unfortunately but two experiments with mixed diet were made with such an apparatus. In both of these experiments the basal value was determined in several periods just preceding the ingestion of the food.

J. J. C, February 28, 1911

The universal respiration apparatus was used for this experiment of 12 periods (3 periods of fasting and 9 periods after food). The diet consisted of 210 grams black bread, 15 grams sugar, 25 grams butter, and 500 grams coffee, or a total amount of 750 grams. The fuel value of the diet was 796 calories, of which 11 per cent came from protein, 26 per cent from fat, and 63 per cent from carbohydrates. The results of the experiment are given in table 246. In about 1 1/2 hours after the taking of the food, the heat production had increased from 1.16 calories to a maximum of 1.43 calories per minute. At the end of the experiment, nearly 5 hours after the ingestion of food, the heat production had not quite reached the basal value.

Table 246. - J. J. C, February 28, 1911. Lying. (Values Per Minute). Mixed Diet

Amount, 750 grams;1 nitrogen, 3.42 grams; total energy, 826 cals. Fuel value: Total, 796 cals.; from protein, 11 p. ct.; from fat, 26 p. ct.; from carbohydrates, 63 p. ct.

1Includes 500 grams coffee.

2Subject ate between 10h40m and 10h54m a. m.

A. F., April 20, 1915

The second respiration experiment with a mixed diet was made with the Tissot respiration apparatus. The food included 45 grams egg (boiled), 250 grams milk, 37 grams toast, and 12 grams butter, a total of 344 grams. The fuel value of the diet was 468 calories, of which 17 per cent came from protein, 52 per cent from fat, and 31 per cent from carbohydrate. The details of the experiment are given in table 247. The heat production increased from a basal value of 1.27 calories per minute to a maximum of 1.45 calories per minute in approximately 30 minutes after the taking of the food. This was followed by a gradual decrease, but at the end of the experiments nearly 3 1/2 hours after the food had been taken, the basal value had not, been reached.

Table 247. - A. F., April 20, 1915. Lying. (Values Per Minute). Mixed Diet

Amount, 344 grams; nitrogen, 3.04 grams; total energy, 494 cals.

Fuel value: Total, 468 cals.; from protein, 17 p. ct.; from fat, 52 p. ct.; from carbohydrates, 31 p. ct.

1Subject ate between 9h23m and 9h29m a. m.

2Subject sat up between 10h28m and 10h58m a. m. and between 12h and 12h25m p. m.

It is evident that these two respiration experiments throw but little light upon the general course of the metabolism after the taking of a mixed diet. The calorimeter experiments, especially those following an excessive amount of food, showed a pronounced effect upon the metabolism. It is much to be regretted that the experimental procedure of the studies with the calorimeter did not permit the careful separation of the results into short periods, so that we might gain some information as to the exact course of the metabolism, the time relations, and the altitude of the peak effect. While we are able to study more closely these particular points in the short-period respiration experiments with carbohydrate and protein diets, the evidence supplied with mixed diets is slight, suggesting only that the peak effect probably occurred soon after the ingestion of the food.