HOW LIFE CAME TO EARTH 181 



and the process soon comes automatically 

 to an end. 



But when the cell colloid, and chlorophyll, 

 and the inorganic constituents to be acted 

 upon are built up into one chemical whole, 

 and then the sunlight plays upon this complex 

 colloid, molecular vibrations and energy ex- 

 changes are initiated which cause up -building 

 of organic matter and transformation from one 

 organic substance to another. Similarly, in 

 those other cells of plants and animals which 

 possess no green transformer, it is only when 

 the organic matter (built up elsewhere in the 

 green cells and transported to the colourless 

 parts) has become an intrinsic part of the 

 colloidal mass of the new cell, that it can be 

 acted upon and made to part with its energy, 

 or used to form living matter. A molecule of 

 carbohydrate, or fat, or protein, can only 

 form an integral part of living matter, or yield 

 energy to living matter, after it has been 

 assimilated into the colloidal mechanism of 

 the cell and chemically constructed into its 

 mass. 



The substance chlorophyll is itself far 

 too complex to arise as a first step from in- 

 organic matter in the absence of life, yet as 

 the present life-builder of the world, it gives 

 a clue as to what ought to be sought for in 



