IS THE BODY A MACHINE? 51 



compounds and combine them together to form 

 more complex ones in such a way that the total 

 result is an increase of chemical compounds of 

 high complexity. In doing this they use the 

 energy of sunlight, which they then store away 

 in the compounds formed. They thus produce 

 starches, oils, proteids, woods, etc., and these 

 stores of energy now may be used by artificial 

 machines. The living machine builds up, other 

 machines pull down. The living machine stores 

 sunlight in complex compounds, other machines 

 take it out and use it. The living organism is 

 therefore to be compared to a sun engine, which 

 obtains its energy directly from the sun, rather 

 than to the ordinary engine. While this does not 

 in the slightest militate against the idea of the 

 living body as a machine, it does indicate that it 

 is a machine of quite a different character from 

 any other, and has powers possessed by no other 

 machine. Living machines alone increase the amount 

 of chemical compounds of high complexity. 



We must notice, however, that this power of 

 construction in distinction from destruction, is 

 possessed only by one special class of living ma- 

 chines. Green plants alone can thus increase the 

 store of organic compounds in the world. All col- 

 ourless plants and all animals, on the other hand, 

 live by destroying these compounds and using 

 the energy thus liberated; in this respect being 

 more like ordinary artificial machines. The ani- 

 mal does indeed perform certain constructive op- 

 erations, manufacturing complex material out of 

 simpler bodies ; as, for example, making fats out of 

 starches. But in this operation it destroys a large 

 amount of organic material to furnish the energy 

 for the construction, so that the total result is a 



