FOODS — HUMAN NUTEITION. 263 



were made with tlie calorimeter previously described (E. S. R., 27, p. 367). 

 The usual temperature readings were made at 5-miiiute periods. 



From these observations "the heat output of the subject (plus any heat 

 arising from a subsequent conversion of mechanical work into heat) was cal- 

 culated for each 5-minute period and the results platted as curves. By cor- 

 rection from observation these curves, altered by allowances for the storage of 

 heat in the subject, were converted into heat-production curves — that is to say, 

 curves representing the total transformation of energy within the calorimeter." 

 These curves of heat output are "parallel to the surface temperature curves 

 obtained simply by one set of observations during the first half-hour of each 

 'work experiment,' that is to say, so long as the observations of surface tem- 

 perature are not complicated by the accumulated presence of surface moisture, 

 and in some of the extremely light 'work experiments' continue in parallel 

 fashion to the end of the experiment whilst showing corresponding variations 

 at nodal points. . . . 



" It would thus seem as if the transformation of energy per unit of mechanical 

 work performed was a quantity that increased up to a certain value which was 

 then maintained, and that the 'eflEiciency' of man as a machine varied in this 

 fashion with the time spent in work. . . . 



"If it is not the case, then two other lines of explanation have in addition 

 to be examined. Thus it may be that the 'deep temperature' (rectal) is not -'a 

 satisfactory criterion of the mean temperature of the human body and does not 

 therefore provide a proper basis for corrections representing its average storage 

 of heat during any short period (5 minutes) of time. It might, on the other 

 hand, be the case that energy liberated during the performance of mechanical 

 work as the outcome of oxidation processes developed as fully at the com- 

 mencement as at the end of the experiment might be stored within the body, 

 possibly within the musculature, in some form other than heat, as, for example, 

 in the form of electrical energy, and therefore not discoverable by reference to 

 changes of temperature." 



In view of these considerations, the data obtained after the first hour were 

 used in estimating the maintained efficiency of the subjects. The total trans- 

 formation of energy in calories per subject per hour was calculated. 



Previous calibration experiments with the cycle ergometer as driven by a 

 special motor furnished the data for estimating the value in calories of the 

 mechanical work performed by the subjects. Comparing the figures for the 

 second and the fifth hours, an increment of work performance of 29.5 calories 

 per hour was found in the subjects, the increment of increase in their total 

 energj' transformation for the same period being 119, 121, and 120 calories, 

 respectively. 



" It is clear, in the first place, that the ' efficiency ' of these 3 different persons 

 of different ages (45, 24, 36) and of quite different physical appearance and 

 habits is alnjost the same, and in the second place that it is at least ... of the 

 magnitude of 24.6 per cent." 



The energy produced by the processes of oxidation in the org-anism ; 

 physiolog'y of muscular work, R. Hober {Ztschr. Elelctrochem., 19 (1918), Ifo. 

 19, pp. 738-7 Jf6.). — This paper, delivered at the meeting of the Bunsen Society 

 of Applied Physical Chemistry, Breslau, August, 1913, is a summary of the 

 advance made in the knowledge of the chemo-dynamics of muscle from the time 

 of Fick to the present. 



According to the author, a muscle is to be regarded as a chemodynamical and 

 not a thermodynamical machine, since it has so high an effectiveness that one 

 would have to take into account extremely high temperatures if a thermo- 

 dynamical explanation were offered. 



