322 



FOOD INGESTION AND ENERGY TRANSFORMATIONS. 



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. 



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 \ 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. 



'Subject ate between 9 h 23 m and 9 h 29 m a. m. 



^Subject sat up between 10 h 28 m and 10 h 58 m a. m. and between 12 h and 12 h 25 m 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 pro- 

 cedure of the studies with the calorimeter did not permit the caretul 

 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 experi- 

 ments 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. 



