INGESTION OF CARBOHYDRATES. 173 



fat and a splitting off of carbohydrate when large amounts of carbo- 

 hydrate are ingested, with a so-called "atypical" carbon-dioxide produc- 

 tion, unaccompanied by an increase in the oxygen consumption. In 

 other words, this process is entirely aside from the katabolic processes 

 in the body and does not affect the total katabolism appreciably, 

 though there is a slight energy output incidental to the transformation. 



Finally, there may be an actual increase in the total katabolism, 

 which would of itself result in an increased carbon-dioxide production. 

 This increase in the katabolism may be caused by an increased tonus 

 and an increased activity in the digestive tract due to the stimulating 

 effect of the absorbed food materials upon the body cells. It is thus 

 clear that these three processes, which may take place simultaneously 

 in varying degrees of intensity, greatly complicate the interpretation 

 of results based only upon the carbon-dioxide increment. 



The experiments in this research which were designed to study the 

 influence of the ingestion of carbohydrates were planned to measure 

 not only a prolonged effect but particularly to show the maximum 

 carbon-dioxide production and oxygen consumption which might 

 appear early in the observations. In the calorimeter experiments 

 measurements were also made of the heat production. For the 

 respiration experiments the heat production was calculated from the 

 results obtained for the gaseous exchange. A number of carbohydrate 

 food materials were used, including not only pure carbohydrates, 

 such as cane sugar, dextrose, levulose, and milk sugar, but also those of 

 a mixed nature, like bananas and popcorn. As in the series of experi- 

 ments already discussed, the data were secured with the respiration 

 calorimeter at Wesleyan University, Middletown, and with the chair 

 calorimeter and two forms of respiration apparatus at the Nutrition 

 Laboratory, Boston. 



CALORIMETER EXPERIMENTS. 



The agreement between the results obtained by direct and indirect 

 calorimetry in the calorimeter experiments was, in many instances, 

 extremely unsatisfactory, so much so that for a long time we were dis- 

 posed to question the value of our calorimeter measurements, par- 

 ticularly those with the Boston calorimeters. Subsequent experi- 

 mentation has shown, however, that direct and indirect calorimetry 

 may not necessarily agree under the abnormal conditions previously 

 outlined which obtain when excessive amounts of carbohydrates are 

 ingested. 



To secure a satisfactory agreement between direct and indirect 

 calorimetry is a problem that has received a great deal of attention 

 ever since the earliest days of direct measurements of the heat output 

 of man. The attempt was made in all of our experiments to determine 



