THE BREATH OF LIFE 



one another and form compounds of great variety 

 and complexity, characterized by the instability 

 which life requires. The organic compounds are 

 vastly more sensitive to light and heat and air than 

 are the same elements in the inorganic world. What 

 has happened to them? Chemistry cannot tell us. 

 Oxidation, which is only slow combustion, is the 

 main source of energy in the body, as it is in the 

 steam-engine. The storing of the solar energy, 

 which occurs only in the vegetable, is by a process 

 of reduction, that is, the separation of the carbon 

 and oxygen in carbonic acid and water. The chem- 

 ical reactions which liberate energy in the body are 

 slow; in dead matter they are rapid and violent, or 

 explosive and destructive. It is the chemistry in the 

 leaf of the plant that diverts or draws the solar en- 

 ergy into the stream of life, and how it does it is a 

 mystery. 



The scientific explanations of life phenomena are 

 all after the fact; they do not account for the fact; 

 they start with the ready-made organism and then 

 reduce its activities and processes to their physical 

 equivalents. Vitality is given, and then the vital 

 processes are fitted into mechanical and chemical 

 concepts, or into moulds derived from inert matter 

 — not a difficult thing to do, but no more an ex- 

 planation of the mystery of vitality than a painting 

 or a marble bust of Tyndall would be an explana- 

 tion of that great scientist. 



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