70 



FOOD INGESTION AND ENERGY TRANSFORMATIONS. 



of time between the determination of the basal value and that deter- 

 mined after the ingestion of food. 



TABLE 22. A. H. M., February 2-8, 1906. (24-hour periods, 7 a. m. to 7 a. m.) 



Crackers and milk: 1 



Amount, 1,150 grams; nitrogen, 7.34 grams; total energy, 1,314 calories. 

 Fuel value: Total, 1,250 calories; from protein, 15 per cent; from fat, 39 per cent; from 

 carbohydrates, 46 per cent. 



'The food was eaten mostly in three portions, at 9 a. m., 1 p. m., and 6 p. m. Soda crackers 



and graham crackers were used with the milk. 

 2 For period 6 h 15 m a. m. Feb. 2 to 7 a. m. Feb. 3. 



GENERAL CONCLUSIONS REGARDING USE OF 24-HOUR PERIODS. 



From the foregoing discussion of the results of the experiments made 

 on the 24-hour basis, it is seen that serious objections may properly be 

 raised to this type of experiment, even though on first consideration 

 the method may seem theoretically desirable. Experience with fast- 

 ing men, both at Wesleyan University and in the Nutrition Labora- 

 tory, 1 has demonstrated that the metabolism progressively decreases as 

 the fast continues. In the fast studied at the Nutrition Laboratory, 

 in which accurate graphic records of the activity were obtained, this 

 decrease in the fasting metabolism occurred with considerable uni- 

 formity at least 31 days, accompanied by a proportional loss in body- 

 weight. In view of the steady loss in weight, it seems illogical to use 

 values for a base-line which were determined under such conditions, 

 particularly if the values are not compared on the basis of per kilogram 

 of body-weight or per square meter of body-surface. 



Furthermore, the depression in the metabolism due to fasting is 

 abnormal, for evidently we have here a process entirely distinct from 

 that due to the mere absence of food in the digestive tract. If we are to 

 follow the contention of Johansson, we must consider the digestion 

 of food and the daily body metabolism as two entirely independent 

 processes, the body drawing continually upon its several depots for 

 its immediate needs and the ingestion of food resulting in a separate 

 process for replenishing these depots. At the time our studies of the 



'Benedict, Carnegie Inst. Wash. Puh. No. 77, 1907, and No. 203, 191.5. 



