232 FOOD INGESTION AND ENERGY TRANSFORMATIONS. 



possible that the disintegration of sucrose as a result of cleavage may have 

 produced stimulating substances, such as intermediary acid products, 

 in somewhat larger amounts than those occurring in the preparation of 

 levulose for final combustion or storage in the body. The data do not 

 permit of closer analysis in searching for a cause for this variation. It 

 is evident, however, that following the ingestion of sucrose a consider- 

 ably greater stimulus to the metabolism may be expected than that 

 occurring with any of the other sugars, at least so far as the maximum 

 effect is concerned. 



TOTAL INCREMENT IN METABOLISM AFTER CARBOHYDRATE INGESTION 



(INDIRECT CALORIMETRY). 



In the preceding section special emphasis has been laid upon the 

 maximum increment in terms of percentage of the basal value in 

 other words, the absolute height to which the basal metabolism can be 

 increased by the ingestion of different carbohydrates. As was pointed 

 out in the consideration of the calorimeter experiments (see page 200) , 

 the total increment expressed as a percentage value can have but little 

 significance, as the increase may extend over a considerable period of 

 time and the basal value for this time will be directly proportional to 

 the period; consequently the increment represents a continually 

 decreasing percentage of the basal value. For these respiration experi- 

 ments, therefore, it is likewise inexpedient to consider the percentage 

 of total increment as referred to the basal value. On the other hand, it 

 is perfectly feasible to compute the total increment in the metabolism. 

 A series of tables has therefore been prepared showing the computed 

 increments for carbon-dioxide production, oxygen consumption, and 

 heat production in the period of observation following the ingestion of 

 carbohydrate. 



As already explained on page 151, the increment in heat production 

 for practically all of the respiration experiments has been computed 

 from measured areas representing heat values superimposed on a fast- 

 ing base-line observed preceding the ingestion of food. The increases 

 in heat production with carbohydrates were obtained in this manner. 

 The increments for carbon-dioxide production and oxygen consump- 

 tion have been found by a method somewhat different, but yielding 

 practically the same result. As in the case of the plotted area for heat 

 production, values were interpolated for the interval between the time 

 when the subject finished eating and the beginning of the first measured 

 period and for the intervals between the periods of measurement. For 

 the interval preceding the first measured period it was assumed that 

 the increment per minute was one-half that found in the period; for 

 each interval between measured periods the average of the per-minute 

 increments observed in the periods preceding and following the inter- 

 val was used. Multiplication of the duration in minutes of the inter- 



