ENERGY IN BIOLOGY. lOI 



electrical energy. This discovery in the world of 

 energy, which took place, so to speak, before our 

 very eyes, of an agent which plays so large a part 

 in nature, clearly leaves the door open to other 

 surprises. 



We shall therefore concede that there may be 

 other forms of energy at work in living beings than 

 those we already know in the physical world. This 

 reservation would enable us to discover at once the 

 essential characteristics by which vital phenomena 

 are henceforth reduced to universal physics, and 

 the purely formal differences still distinguishing 

 them. 



If there arj really special energies in living beings, 

 our monistic postulate leads us to assert that these 

 energies are homogeneous with the others, and that 

 they do not differ from them more than they differ 

 among themselves. It is probable that some day 

 they will be discovered external to living bodies, if 

 the material conditions (which it is always possible to 

 imagine) are realized externally to them. And if we 

 must admit that the peculiarity of the medium is 

 such that these forms must remain indefinitely 

 peculiar to living beings, we may assert with every 

 confidence that these special energies do not obey 

 special laws. They are subject to the two funda- 

 mental principles of Robert Mayer and Carnot. 

 They are exchanged according to fixed laws with 

 the other physical forms of energies at present 

 known. 



To sum up, then, we must establish three categories 

 in the forms of energy which express the phenomena 

 of vitality. 



In the first place, most of these energies are those 



