204 FOOD INGESTION AND ENERGY TRANSFORMATIONS. 



In practically all of the observations with the respiration apparatus, 

 the basal value was determined each day just prior to the ingestion of 

 the carbohydrate studied, usually as a result of 2 to 4 well-agreeing 

 periods. From the results obtained with the calorimeter experiments, 

 it was clear that a greatly increased production of carbon dioxide was 

 to be expected after the ingestion of the carbohydrate and that this 

 might persist for some time, but that the increase in the oxygen con- 

 sumption would probably not continue for a great length of time. 

 Hence most of our respiration experiments were terminated 3 to 4 

 hours after the ingestion of the carbohydrate; occasionally some 

 experiments were even shorter than this. In no instance were the 

 experiments continued for 8 hours, as was frequently the case in the 

 calorimeter experiments. The periods were usually 15 minutes long, 

 but in one or two experiments they were much shortened for the pur- 

 pose of studying the rapid fluctuations in the respiratory quotient. 1 



Only pure carbohydrates were used in the respiration experiments, 

 i. e., dextrose, levulose, sucrose, and lactose. These carbohydrates 

 may be considered as chemically pure products, save that levulose and 

 lactose contain a small percentage of water. 2 The amounts given were 

 in practically every experiment either 100 or 75 grams. In many of 

 the experiments the sugars were taken in solution, water and varying 

 amounts of lemon juice being added. As a rule, the juice of one-half 

 or a whole lemon was used, this being approximately 20 or 40 grams. 



A large number of subjects were studied and sufficient data secured 

 to draw general deductions, but it should be borne in mind that the 

 individual values must not be considered as indicative of the indi- 

 viduality of the subject or of any particular abnormality. With the 

 universal respiration apparatus, duplicate gas analyses are not made; 

 the measurements of the carbon-dioxide production and oxygen con- 

 sumption for each period therefore represent only individual determin- 

 ations. This fact should be especially emphasized, as with practically 

 all other forms of respiration apparatus duplicate gas analyses are the 

 rule. 



STATISTICS OF RESPIRATION EXPERIMENTS. 



With so large a number of respiration experiments, it seems needless 

 to discuss them individually; hence only the statistical data are given 

 here, grouped according to the carbohydrate used, with the idea of 

 including the results later in general summary tables and discussing 

 not only the influence of the individual carbohydrates upon the basal 

 metabolism, but likewise the effect of variations in the amounts in- 

 gested. The preliminary experiments with the universal respiration 

 apparatus on the influence of the ingestion of food were made with the 



1 See, for instance, tables 134 and 146, pp. 209 and 214. 



2 The levulose contained 4.8 per cent moisture; lactose having one molecule of crystallization 

 was always used. 



