98 ORIGIN AND NATURE OF LIFE 



there is formed the substance called carbonyl 

 chloride, of which the molecule contains one 

 carbon atom, one oxygen atom, and two 

 chlorine atoms. If, more simply, the carbon 

 monoxide is burnt in the air, one extra atom 

 of oxygen enters into relationship to the two 

 affinities of the carbon, and the very common 

 substance carbon-dioxide is formed. This 

 body is present in minute amounts in the air, 

 and it is of interest to note here that from it 

 the green plant is able when it is aided by 

 the energy of the sunlight, to build up those 

 organic substances of complex nature found 

 in living plants. 



It is a curious fact that all life on the earth 

 should depend upon two simple factors, (1) the 

 presence of a mere trace, lying at the level of 

 only between three and four parts per 10,000, 

 of this gas in the air, and (2) the natural 

 power of the carbon atom contained in the 

 carbon-dioxide, of entering into energy rela- 

 tionships with fellow carbon atoms. Given 

 these conditions, a suitable form of energy, 

 and a suitable machine or transformer for 

 that energy capable of turning it into chemical 

 energy of carbon compounds, and it follows 

 that all the complex organic constituents which 

 form the basis of life not only can, but musU 

 arise. 



