INGESTION OF CARBOHYDRATES. 175 



Since it is the custom of many writers to compute the non-protein 

 respiratory quotient and determine the non-protein metabolism in 

 experiments of this kind, values for the nitrogen excretion in the urine 

 have been given whenever obtainable, but with no idea of indicating 

 the influence of the ingested food. Although basal values for nitrogen 

 have been included in the tables whenever available, no effort was made 

 to obtain such data for our experiments. In this we find ourselves at 

 variance with Gigon, who assumed that the basal value for nitrogen 

 was constant. It should be emphasized, however, that this research 

 was not planned to study the influence upon the protein katabolism 

 of the ingestion of the various foods studied. The non-protein respi- 

 ratory quotient is not of special significance in this research and it is 

 deemed unwise to expand the data by including it, especially as it may 

 be computed from the values for the nitrogen excretion as follows : 



From the computations of Zuntz it is assumed, for the period in 

 which the non-protein quotient is desired, that for each gram of nitro- 

 gen determined in the urine 5.91 liters of oxygen are absorbed and 4.75 

 liters of carbon dioxide are produced. The values obtained by multi- 

 plying these amounts of oxygen and carbon dioxide by the grams of 

 nitrogen are considered to represent the carbon dioxide produced and 

 oxygen consumed in the disintegration of the protein. Since the total 

 oxygen consumption and carbon-dioxide production are determined, 

 the subtraction of the amounts resulting from the katabolism of protein 

 gives the liters of oxygen absorbed and carbon dioxide produced in the 

 katabolism of fat and carbohydrate; the quotient from the division 



CO 



of the amounts so obtained, -^p, will thus be the non-protein respira- 



tory quotient. 



If it is further desired to compute the heat produced by the katab- 

 olism of body material, the grams of nitrogen in the urine multiplied by 

 26.51 calories 1 will give the heat production resulting from the oxidation 

 of protein. By employing the calorific value of oxygen found in the 

 table of Zuntz 2 for the non-protein quotient obtained in the above 

 calculation, the heat that should result from the katabolism of the fat 

 and carbohydrate is obtained. The sum of these computed values 

 for protein and for fat and carbohydrate constitutes the heat produced 

 (computed) for the period under observation. 



In discussing the results of the experiments with carbohydrates, the 

 experiments made with the Middletown and Boston calorimeters will 

 first be considered and subsequently those made with the respiration 

 apparatus in Boston. Except in one instance, the experiments in 

 Middletown were carried out in 2-hour periods; in the Boston experi- 

 ments the periods were only an hour in length, and the basal metabo- 

 lism was usually determined on the same day. 



, Oppenheimer's Handbuch der Biochemie, 1911, 4 (1), p. 279. 

 2 Zuntz and Schumburg, Physiologic des Marsches, 1901, p. 361. 



