148 THE MECHANISM OF LIFE 



sugar and fat, the nitrogen and the sulphur into albumen, 

 and the compounds so formed are then said to belong to the 

 organic world. These organic bodies are returned once again 

 to the mineral world by the action of animals and microbes, 

 which transform the carbon into carbonates, and the nitrogen, 

 sulphur, and phosphorus into nitrates, sulphates, and phosphates. 

 Hence life is but a phase in the animation of mineral matter ; 

 all matter may be said to have within itself the essence of life, 

 potential in the mineral, actual in the animal and the vegetable. 

 The flux and reflux of matter is alternate and incessant, from 

 the mineral world to the living, and back again from the 

 living to the mineral world. 



At the same time there is a continuous flux of energy. 

 Organic matter contains potential energy, the energv o\' 

 chemical combination ; and during its passage through the 

 living being it is gradually stripped of this energv and returned 

 to the mineral world. The first step in synthetic biology i> 

 the addition of potential energy to matter, the reduction of 

 an oxide, the separation of a salt into its radicals, the pro- 

 duction of some endothermic chemical combination. The 

 energy stored up by such processes can he again liberated as 

 heat, that fire which the ancients with wonderful prescience 

 long ago recognized as the symbol of life. 



Attempts have been made to differentiate a living being hv 

 the nature of its chemical combinations, the so-called organic 

 compounds. It was supposed that life alone could realize 

 these and cause the production of the various substances which 

 ■form the structure of living beings. Of late years, however, 

 a large number of these organic substances have been artificially 

 produced in the laboratory, and the synthetic problems which 

 remain are of the same order as those which have been already 

 solved. 



As one learns to know the mineral kingdom and the living 

 world more intimately the differences between them disappear. 

 Thus a living being was supposed to be characterized by its 

 sensibility, i.e. its faculty of reaction against external im- 

 pressions. But this reaction is a general phenomenon of 

 nature: there is no action without reaction. Neither can the 



