THE THEORY OF ENERGY AKD THE LrVING WORLD. 

 THE PHYSIOLOGY OF ALIMENTATION. 1 



By A. Dastre. 



I. — GENERAL DISCUSSION OF ENERGY/ 



A new term, that of energy, was introduced in the natural sciences 

 some years ago, and its significance has continually increased in impor- 

 tance. The English physicists, and especially the English electricians, 

 have had most to do in bringing this new expression into scientific tech- 

 nology. The idea which it conveys is of the highest utility in its indus- 

 trial applications, and it was from an industrial origin that the term has 

 been expanded and generalized. It is now, however, not merely of 

 practical signification, but a theoretical conception of capital impor- 

 tance in pure science. It has indeed come to the point of being in itself 

 a science — energetics, so called. Although born bat yesterday, this 

 new comer claims to embrace and fuse together in itself all the other 

 natural sciences, both physical and pertaining to life, which only the 

 imperfect condition of our knowledge had till now kept separate and 

 distinct. 



At the threshold of this new science we must inscribe the principle 

 of the conservation of energy, of which it may well be said that it 

 dominates natural philosophy. The discovery of this principle has 

 marked a new era and accomplished a j>rofound revolution in our con- 

 ception of the universe. It is due to a physician, Robert Mayer, who 

 practiced his art in a small village of Wiirtemberg. He formulated 

 the new principle in 1842, and successively developed its consequences 

 in a series of publications which appeared between 1845 and 1851. These 

 remained, however, almost unnoticed and ignored until Helmholtz, in 

 his celebrated memoir upon the conservation of force, placed them 



'Translated from Revue des Deux Mondea, 1898, Vol. CXLVI, pp. 668-683; Vol. 

 CXLVII, pp. 189-204; and Vol. CL, pp. 201-216. 



2 References: Paul Janet, Premiers principes d'electricite industrielle, Paris, 1893; 

 Ch. Friedel, Preface au Traite de chimie organique de A. B6hal, Paris, 1896; W. 

 Ostwald, Abrege de chimie ge"nerale, Paris, 1893; A. Bouasse, Introduction a 

 l'etude des theories de la mecanique, 1895; A. Reychler, Les Themes physico-chim- 

 iques, 1897; H. Le Chatelier, Sur l'Energetique, Revue des sciences, 1893. 



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