152 ESSAYS OF A BIOLOGIST 



matter is merely a special and highly complicated 

 form of ordinary matter ; and there can be no reason- 

 able doubt that it has originated naturally from non- 

 living matter. 



While the main direction of the inorganic has been 

 towards degradation of energy, it has shown another 

 subsidiary direction towards the production of more 

 and more complex forms of matter. If our general 

 ideas are correct, there must have been a time when 

 matter in our ordinary sense of the word did not 

 exist — there can have been no atoms, only free 

 electrons. From this state there evolved one in 

 which the various electron-systems that we call 

 atoms first appeared ; later still atoms could join 

 with atoms to produce molecules. Leaping over 

 vast periods, we would come to the time when radia- 

 tion had brought the temperature of the earth surface 

 below 100 degrees centigrade ; water then could 

 form from steam and solution occur. Through 

 solution, all soluble elements, which would otherwise 

 remain locked in the inactivity of the solid state, are 

 enabled to enter upon a new phase of mobility, of 

 chemical life, as we may say. Only in water could 

 colloid carbon compounds first be built up, and only 

 from such substances could life originate. 



Living substance, or at least much of it, must be 

 formed of molecules containing thousands of atoms, 

 each atom in its turn a system of circling electrons. 

 Here already is a vast increase of complexity : it 



