Energy Balance. 511 



Experiment No. 51 immediately followed a 1-day experiment, No. 50, in which 

 the subject was distinctly ill. He was compelled to stop the work experiment 

 in which he was engaged and lie down during the day, consuming but a small 

 quantity of food. Therefore, the effect of the preliminary day before the 2 

 days of fasting may have been such as to cause errors either in the results of 

 analyses or the heat measurements. There is a strong probability, too, that 

 after the severe muscular work on the 3 days preceding experiment No. 50, the 

 store of glycogen in the body had been heavily drawn upon and, therefore, 

 did not undergo material alteration during fasting. Against this latter suppo- 

 sition is the fact that for the 3 days of experiment No. 49, although the subject 

 worked very severely, he was supplied with a very large amount of carbo- 

 hydrates in the diet, and analyses showed that during the last 2 days of the 

 experiment, there was a small gain of carbon to the body. On the contrary, 

 there was a marked loss of carbon with probably heavy drafts upon previously- 

 stored glycogen in the 1-day experiment No. 50, which immediately preceded 

 the 2 days of fast. The results, then, in all of the earlier experiments would 

 imply that a very material error is present when the assumption is made that 

 the glycogen content of the body remains constant, save in experiments where 

 the store of glycogen has previously been considerably depleted. 



Since the apparatus used in connection with these experiments permitted 

 the direct measurement of heat, the estimated energy of material oxidized from 

 the body can be compared directly with the heat production, and since the 

 law of the transformation of energy holds true in the human body, the accuracy 

 of the method of estimating the heat production from the total katabolism can 

 be checked. For purposes of comparison, the estimated energy of katabolized 

 body material, the total heat production, and the differences between the total 

 heat production and the energy from body material, expressed both in terms of 

 calories and per cent, are given in table 244. 



The widest discrepancy noted on any day during inanition is on the fifth 

 day of experiment No. 73 where the estimated energy of katabolized body 

 material was 66 calories greater than the total heat production, a discrepancy 

 amounting to -|- 4.3 per cent. On the last 2 days of experiment No. 74 (with 

 food), there were discrepancies of -j-4.3 and -(-3.9 per cent, respectively. 

 Usually the discrepancies are extremely small. Thus in the average of 43 

 days of experiments without food, the estimated energy of katabolized body 

 material, 1937 calories, was but 13 calories greater than the average total heat 

 production, a discrepancy of -+- 0.7 per cent. A somewhat greater discrepancy 

 was observed in the smaller number of food experiments, the estimated energy 

 from body material, 1879 calories, being 20 calories greater than the total 

 heat production, corresponding to a discrepancy of -f- 1.1 per cent. The aver- 

 age for all the experiments here published covering 53 days, with and without 

 food, shows a discrepancy of -f- 0.7 per cent. 



