Influence of Ixaxitiox ox Metabolism. 



different sources. The difference between these two quantities is shown in 

 column h and the percentage discrepancy is given in the last column. 



The difficulties of striking an accurate balance of this kind for an experiment 

 of 24 hours' duration are obvious, since there are a number of physiological 

 errors involved which preclude extremely accurate work. On the other hand, 

 if the experimental period be made to cover several days, the physiological 

 errors may and doubtless do in a large measure compensate. From the average 

 of the three days of this experiment, it appears that the average heat production 

 as measured by the calorimeter with corrections is 36 calories less than the 

 estimated energy derived from the different sources or an error of 4- 1.7 per 

 cent. Further discussion of the magnitude of this error and its relation to other 

 experiments is deferred. 



In computing the percentage discrepancy between the total heat production 

 and the estimated energy of material oxidized in the body the former is 

 used as the standard of measurement and the error assumed to be due to the 

 estimates of the energy of material oxidized in the body. Although the direct 

 measurement of oxygen furnishes data for a more exact estimation of the 

 products of katabolism than has heretofore been obtained, it is believed that 

 at present the errors in the assumption of the energy of material katabolized 

 in the body are greater than the errors in the determination of the heat pro- 

 duction and hence the latter factor is used as the standard for comparison. It 

 is to be noted, however, that not only in this, but in the whole series of experi- 

 ments here reported, the agreement between the total heat production and the 

 estimate of the energy of body material actually oxidized is, on the whole, very 

 satisfactory. 



Relations between Oxygen Consumption, Carbon Dioxide Elimination, and Heat 



Production. 



Since heat is the result of the oxidative processes in the body it is natural 

 to suppose that there would be some simple relations existing between the 

 quantities of oxygen absorbed, the quantities of carbon dioxide eliminated, 

 and the heat produced. The data on this point are given in table 20. 



In earlier experiments, where the amounts of oxygen and carbon dioxide 

 were determined, the heat was not directly determined, but the ratio of the 

 respiratory gases has been of great value in estimating the heat production. 



Oxygen thermal quotient. The ratio between the amount of oxygen con- 

 sumed and the amount of heat produced may be termed the oxygen thermal 

 quotient, and this ratio can be expressed as the number of grams of oxygen 

 that is absorbed to produce 100 calories of heat. 



The ratios between the oxygen, carbon dioxide, and heat are of interest not 

 only for the whole day, but also for the shorter periods, and hence in column c 

 the oxygen thermal quotient for each 3-hour period has been recorded. 



