428 THE HUMAN BODY. 



ioot-pounds) of energy. If, therefore, we know how much 

 urea a man excretes during a given time, and how much 

 mechanical work he does during the same time, we can 

 readily discover if the latter could possibly have been done 

 by the energy set free by proteid decomposition. Let us 

 take a special case. Fick and Wislecenus, two German 

 observers, climbed the Faulhorn mountain, which is 1956 

 meters (about 6415 feet) high. Tick weighed 66 kilograms 

 and, therefore, in lifting his Body alone, did during tho 

 ascent. 129,096 kilogrammeters (932,073 foot-pounds) oi 

 work. "Wislecenus, who weighed 76 kilograms, did similarly 

 148,656 kilogrameters (1,073,296 foot-pounds) of work. 

 But during the ascent, and for five hours afterwards, Tick 

 secreted urine containing urea answering only to 37.17 

 grams of proteid, and Wislecenus urea answering to 37 

 grams. Since each gram of proteid broken up in the Body 

 liberates 1805.7 kilogrammeters (13,037 foot-pounds) of 

 energy, the amount that Fick could possibly have obtained 

 from such a source is 1805.7 X 37.17 = 67,117 kilogram- 

 meters (484,584 foot-pounds), and Wislecenus 1805.7 X 37 

 = 66,810 kilogrammeters. If to the muscular work done 

 in actually raising their bodies, we add that done simul- 

 taneously by the heart and the respiratory muscles, and in 

 such movements of the limbs as were not actually concerned 

 in lifting their weight, we should have, at least, to double 

 the above total muscular work done; and the amount of 

 energy liberated meanwhile by proteid oxidation, becomes 

 iitterly inadequate for its execution. It is thus clear that 

 muscular work is not wholly done at the expense of the 

 oxidation of muscle proteid, and it is very probable that 

 none is so done under ordinary circumstances, for the urea 

 excretion during rest is about as great as that during 

 work, if the diet remain the same; if the work is very 

 violent, as in long-distance walking matches, the urea quan- 

 tity is sometimes temporarily raised but this increase, 

 which no doubt represents an abnormal wear and tear of 

 muscle-fibre, is probably independent of the liberation of 

 energy in the form in which a muscle can use it, more 

 likely taking the form of heat; and is, moreover, compen- 



