106 LIFE AND DEATH. 



The second truth taught us by general physiology, 

 a truth which physiology learned from experiment, is 

 enunciated as follows :^The maintenance of life con- 

 sumes none of its energy. It borrows from the external 

 world all the energy which it expends , and borrows it in 

 the form of 'potential chemical energy^} This is a trans- 

 lation into the language of energetics of the results 

 acquired in animal physiology during the last fifty years. 

 No comment is needed to exhibit the importance of 

 such a truth. It reveals the origin of animal activity. 

 It reveals the source from which proceeds that energy 

 which at some moment of its transformations in the 

 animal organism will be a vital energy. 



The prinmm movens of vital activity is, therefore, 

 according to this law, the chemical energy stored up 

 in the immediate principles of the organism. 



Let us try to follow, for a moment, this energy 

 through the organism and to specify the circumstances 

 of its transformations. 



Organic Functional Activity, and the Destruction of 

 Reserve-stuff. Let us suppose then, for this purpose, 

 that our attention is directed to a given limited part 

 of this organism, to a certain tissue. Let us seize 

 it, so to speak, by observation at a given moment, 

 and let us make an examination of the functional 

 activity starting from this conventional moment. 

 This functional activity, like all other vital pheno- 

 mena, will be the result, as we have just explained, of 

 a transformation of the potential chemical energy 

 contained in the materials held in reserve in the 

 tissue. This is our first perceptible fact. This 

 energy, when disengaged, will furnish to the vital 

 action the means by which it may be prolonged. 



There is, then, a functional destruction. There is, at 



