CHAPTER XXIII 



THE STUDY OF LIFE AND THE CONSERVATION OF 

 ENERGY NEW PROOF THAT LIFE IS A PHE- 

 NOMENON SUBJECT TO THE LAWS OF MECHANICS 



ONE of the most important conquests of man's science in 

 the nineteenth century was the discovery of principles of 

 equivalents summed up in the general law of the Conserva- 

 tion of Energy. Energy manifests itself in the world in a 

 great number of forms, mechanical motion, heat, electricity, 

 chemical change, etc. In a system of bodies forming one 

 complete whole, that is, in a system which neither borrows 

 from nor gives to its environment, there disappears a certain 

 quantity of the energy known in one or other of the forms 

 enumerated ; but, in other possible forms, energy appears 

 in corresponding quantities so that the sum of all these new 

 quantities multiplied, each on its own account, by a constant 

 coefficient, reproduces integrally the quantity which has 

 disappeared. 



The energy lost in a waterfall is integrally found again 

 in the heating of its water and of the stones of its bed and, 

 in a way much easier to verify and measure, in the electric 

 energy of a dynamo driven by it, or in the chemical energy 

 of accumulators charged by the dynamo. 



The old ideas about life dated from a time when principles 

 of equivalents were unknown. They are naturally in 



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