IS THE BODY A MACHINE? 65 



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 

 machines. Green plants alone can thus increase 

 the store of organic compounds in the world. All 

 colourless plants and all animals, on the other 

 hand^'live by destroying these compounds and w 

 using the energy thus liberated ; in this respect 

 being more like ordinary artificial machines. The 

 animal does indeed perform certain constructive 

 operations, manufacturing complex material out 

 of simpler bodies ; as, for example, making fats 

 out of starches. But in this operation it de- 

 stroys a large amount of organic material to 

 furnish the energy for the construction, so that 

 the total result is a degradation of chemical 

 compounds rather than a construction. Con- 

 structive processes, which increase the amount 

 of high compounds in nature, are confined to the 

 living machine, and indeed to one special form 

 of it, viz., the green plant. This constructive 

 power radically separates the living from other 

 machines ; for while constructive processes are 

 possible to the chemist, and while engines mak- 

 ing use of sunlight are possible, the living 

 machine is the only machine that increases the 

 amount of high chemical compounds in the 

 world. 



