198 FOOD INGESTION AND ENERGY TRANSFORMATIONS. 



with Dr. R., February 21, 1907, with the maltose-dextrose mixture; 

 H. R. D., April 21, 1906, with bananas and sugar; and A. H. M., 

 April 10, 1907, with popcorn. 



The general conclusions from this series of calorimeter experiments 

 would therefore be that the ingestion of pure or nearly pure carbohy- 

 drate produces a positive increase in the metabolism which for short 

 periods, at least, may amount to almost 35 per cent, and that this 

 increase nearly always takes place in the first 2 hours of experimenta- 

 tion. An examination of tables 101 to 122 shows clearly that results 

 obtained in the periods subsequent to the first 2 hours of the experi- 

 ment give very little, if any, evidence as to the nature of the metab- 

 olism, save that a persistent increase in the carbon-dioxide production 

 is usually found. It is of particular significance, however, that in the 

 majority of the experiments direct calorimetry shows definitely an 

 increment in the heat production due to the ingestion of carbohydrates ; 

 we can therefore consider this fact as established. The value of this 

 known fact will be more apparent when an analysis is attempted of the 

 intermediary processes involved in the metabolism of carbohydrate. 



On the other hand, we are not able from these calorimeter experi- 

 ments to determine with great exactness the time relations between 

 the ingestion of carbohydrate and the metabolism. While they bring 

 out the fact that the maximum effect of carbohydrate ingestion appears 

 in the first 2 hours and that thereafter practically no effect is noted 

 in the majority of instances save in the production of carbon dioxide, 

 experiments made with shorter periods are absolutely essential for a 

 more careful analysis of the relationship. For these determinations in 

 shorter periods recourse must be had to the long series of obser- 

 vations in the respiration experiments with carbohydrates, from which 

 an estimation may be made by indirect calorimetry of the course 

 of the metabolism after carbohydrate ingestion. 



TOTAL INCREMENTS IN METABOLISM AFTER CARBOHYDRATE INGESTION 



(DIRECT CALORIMETRY). 



The discussion thus far has dealt primarily with the extent to which 

 the basal metabolism may be increased temporarily by the ingestion 

 of varying amounts of carbohydrates and the time relations between 

 the maximum increase and the time of ingestion. As a casual exam- 

 ination of tables 101 to 122 will show, the increase in the heat pro- 

 duction after carbohydrate ingestion is, for the most part, only found 

 in the first hour or two. In a number of the experiments the increment 

 continues longer than the first period; it is thus important to note not 

 simply the highest point to which the basal metabolism may be lifted 

 by the ingestion of carbohydrate, but likewise the total effect of the 

 carbohydrate upon the basal metabolism. This can be done only by 



