198 SECTIONAL ADDRESSES 



of muscular work in a respiratory calorimeter ; but their results were 

 published thirty years ago and seem to have been overlooked. They 

 found that for the same amount of work the heat output was practically 

 the same on a mixed diet containing roughly equal proportions of carbo- 

 hydrate and fat as on a carbohydrate diet. Comparing the best two 

 experiments when equal amounts of work were accomplished — 63 and 

 62 on A.L.L. — the total heat output for 3 days was 14670 • i and 14464-4 

 Calories respectively, a decrease on the carbohydrate diet of only i • 4 per 

 cent. The COj values were 1298-4 and 1397 grms. and the oxygen 

 values were 4317-2 and 4058-3 grms. ; these differences are like those 

 that Krogh and Lindhard subsequently found ; the R.Q's. were o - 802 

 and o - 896. The results cannot be explained on the older theory because 

 the heat remained nearly the same on the two diets ; but on the theory 

 of the constant combustion ratio, because the CO 2 was increased on the 

 carbohydrate diet, the combustion of the normal carbohydrate-fat mixture 

 must have been increased and more heat produced ; this increase of heat 

 must have been neutralised by the heat absorbed in the conversion of 

 carbohydrate to fat, a process that, must have occurred, because less oxygen 

 was absorbed on the carbohydrate diet. 



To obtain quantitative evidence of this conversion regression equations 

 of the heat— CO2 and Oj — heat relations for A.L.L. on the two diets 

 have been calculated for 6 hourly periods in all experiments, omitting the 

 first periods in Experiments 62, 63 and 65, which were transition periods 

 as regards diet, but adding the basal determinations in Carnegie Inst. 

 Publication 261 to the mixed diets ; CO 2 and O2 are expressed in grms. : 



Mixed diet : Cals. = 2-94CO2 +45-1. • (10) 



O2 = 0-303 Cals. — lo-i . . (11) 



Carbohydrate diet : Cals. = 2-7iC02 +42-5 . . (12) 



O2 =0-288 Cals. — 0-4 . . (13) 



Suppose 400 grms. COg is excreted on the mixed and on the carbo- 

 hydrate diets the calories from equations 10 and 12 are 1221 and 1128, 

 i.e. with less muscular work there were 93 less calories given out on the 

 carbohydrate diet. From equations 11 and 13 the oxygens corresponding 

 to these heats are 359-5 and 324-6 grms. — i.e. 34-9 grms. less oxygen 

 was absorbed on the carbohydrate diet ; on passing from the mixed 

 to the carbohydrate diet the heat absorbed per grm. of oxygen was 



— =2-66 Cals., or 2 - 66 ~—^ = 3 • 8 Cals. per litre of oxygen ; now the 



34-9 22-4 



theoretical value for the conversion of carbohydrate to fat is 3 -93. Similar 

 calculations over the range of COj's obtained in the muscular work and 

 following rest period gave results as follows : 



CO2 grm. per 6 hours ..... 250, 400, 600, 700 

 Heat absorbed in conversion, Cals. per 6 hours. 59-6, 93, 138, 166 

 Cals. per litre of O2 absorbed in conversion . 7-48, 3 -8, 3 -44, 3 -38 



At any rate the experimental figures are of the same order as the theoretical 

 figure 3-93. 



