HI THE MEANING OF EVOLUTION 267 



Now, whence comes the energy ? From the ingested 

 food, for food is a kind of explosive, which needs only 

 the spark to discharge the energy it stores. Who has 

 made this explosive ? The food may be the flesh of 

 an animal nourished on animals and so on ; but, in 

 the end it is to the vegetable we always come back. 

 Vegetables alone gather in the solar energy, and the 

 animals do but borrow it from them, either directly or 

 by some passing it on to others. How then has the plant 

 stored up this energy ? Chiefly by the chlorophyllian 

 function, a chemicism sui generis of which we do not 

 possess the key, and which is probably unlike that of 

 our laboratories. The process consists in using solar 

 energy to fix the carbon of carbonic acid, and thereby 

 to store this energy as we should store that of a water- 

 carrier by employing him to fill an elevated reservoir : 

 the water, once brought up, can set in motion a mill or 

 a turbine, as we will and when we will. Each atom of 

 carbon fixed represents something like the elevation 

 of the weight of water, or like the stretching of an 

 elastic thread uniting the carbon to the oxygen in the 

 carbonic acid. The elastic is relaxed, the weight falls 

 back again, in short the energy held in reserve is 

 restored, when, by a simple release, the carbon is per 

 mitted to rejoin its oxygen. 



So that all life, animal and vegetable, seems in its 

 essence like an effort to accumulate energy and then to 

 let it flow into flexible channels, changeable in shape, at 

 the end of which it will accomplish infinitely varied 

 kinds of work. That is what the vital impetus, 

 passing through matter, would fain do all at once. 

 It would succeed, no doubt, if its power were un 

 limited, or if some reinforcement could come to it from 

 without. But the impetus is finite, and it has been 



