INGESTION OF CARBOHYDRATES. 225 



respiratory quotients for the same day were not obtained in many 

 cases, we may note that most of the quotients after the ingestion of 

 carbohydrate showed a value of 0.90 or above. Since the average 

 respiratory quotient of normal man in the post-absorptive condition 

 is not far from 0.83, it is obvious that these quotients above 0.90 sub- 

 stantiate the general observation that the respiratory quotient after 

 carbohydrate ingestion is usually decidedly increased. 



In the computation of the heat production from the oxygen con- 

 sumption and the respiratory quotient, a difficulty is immediately 

 encountered in the fact that the respiratory quotient is frequently over 

 1, especially the non-protein respiratory quotient. Experimental evi- 

 dence as to the calorific value of oxygen and carbon dioxide under 

 these conditions is much needed. An investigation of this problem is 

 now in progress in this laboratory; pending its completion we have 

 assumed, in common with other investigators, that when the quotient 

 is above 1, the calorific values of carbon dioxide and oxygen are the 

 same as those when the quotient is 1. The computations of the heat 

 production were based entirely upon the oxygen consumption, since the 

 carbon-dioxide excretion is greatly increased as a result of intermediary 

 metabolism, with a possible splitting off of carbon dioxide accompanied 

 by only minor increases in the production of heat. 



MAXIMUM EFFECT ON METABOLISM OF CARBOHYDRATE INGESTION 



(INDIRECT CALORIMETRY). 



We have reason to believe that not only the different sugars but also 

 the different amounts of sugars vary somewhat in regard to the actual 

 height to which the metabolism may be increased and the time when 

 the maximum metabolism appears. It is important, therefore, to 

 determine as accurately as possible both of these factors. In the calo- 

 rimeter experiments it was found that the maximum heat production 

 occurred some time during the first or second hour. Since in the res- 

 piration experiments observations are made every 15 or 20 minutes, it 

 is possible to determine with considerable accuracy when the maximum 

 or "peak" effect of carbohydrate ingestion appears. This is shown 

 for the carbon-dioxide excretion, oxygen consumption, and heat pro- 

 duction for all of the respiration experiments in tables 169 to 172. 



DEXTROSE. 



Ten experiments were made with 100 grams of dextrose with 9 

 subjects and four experiments with 75 grams of dextrose with two 

 subjects. The greatest percentage increments are shown in table 169. 

 In the experiments with 100 grams of dextrose the carbon-dioxide 

 maximum increments show very large values. Thus, in no experi- 

 ment was the maximum increment in the carbon-dioxide production 



