A HISTORY OF METABOLISM 



25 



that the discrepancy between the quantity of expired carbonic acid and 

 inspired oxygen, which he had observed in 1780, was accounted for by the 

 fact that a part of the absorbed oxygen was utilized to oxidize hydrogen 

 in the lungs. This oxidation would produce additional heat and 'account 

 t'<>r the discrepancy between the heat directly measured from a guinea-pig 

 and the heat calculated as being derivable from the oxidation of carbon by 

 oxygen. It is interesting to recall that eighty years later, in I860, 

 Eischoff and Voit still calculated the heat value of the metabolism from 

 the heat which would be produced in burning the carbon and hydrogen 

 elements of the metabolism. 



Respiration experiments on a human being constituted the final con- 

 tribution in the culmination of this great career. The work is presented 

 by Seguin and Lavoisier (/) in the memoirs of the Academic des Sciences 

 during the year 1789. In this paper the authors remark: "This analogy 

 between combustion and respiration did not escape the attention of the 

 poets and philosophers of antiquity, of which they were the interpreters 

 and spokesmen. Fire taken from the heavens, this flame of Prometheus, 

 not only represents an idea that is ingenious and poetical but it is a true 

 picture of the operations of nature on behalf of animals who respire; one 

 can say with the ancients that the fire is lighted the moment a baby takes 

 its first respiration and is not extinguished until its death." 



Before giving the details of the experiments on man the authors 

 state that a guinea-pig respired in pure oxygen and in a mixture of oxygen 

 and hydrogen gas just as it did in ordinary air; respiration, circulation 

 and the intensity of combustion were uninfluenced. Nitrogen had nothing 

 to do with respiration. 



In the experiments on man Segnin himself was the subject. The 

 resiilts are given in the accompanying table: 



RESULTS OF EXPERIMENTS OX MAN 



Here are the basic facts regarding metabolism. The basal metabolism 

 was increased 10 per cent after exposure to cold; 50 per cent after taking 

 food; 200 per cent by exercise; and 300 per cent on combining- the influ- 

 ences of food and exercise. We now know more details and we may also 

 calculate that Lavoisier's determination of 24 liters of oxygen absorbed 



