THE BEGINNINGS OF LIFE. 103 



light in the leaves of plants. Among the several 

 elements concerned there are wide differences in mole- 

 cular mobility, and probably in the rates of molecular 

 vibration. Each is combined with many of the others, 

 but is capable of forming various combinations with 

 the rest. And they are severally in presence of a com- 

 plex compound into which they all enter, and which 

 is ready to assimilate to itself the new compound 

 atoms that they form. Certain of the ethereal waves 

 falling on them when thus arranged, there results 

 a detachment of some of the combined atoms and 

 a union of the rest. And the conclusion suggested 

 is, that the Induced vibrations among the various atoms as 

 at first arranged, are so incongruous as to produce instability j 

 ana 1 to give collateral affinities the power to 'work a re- 

 arrangement which^ though less stable under other conditions^ 

 is more stable in the presence of these particular undulations? 

 Thus the way seems opening for us to comprehend 

 how, under the mere influence of physical forces, not- 

 living combinations may be broken up so as to give 

 place to those more subtle combinations of matter 

 which are only possible where much incident force is 

 retained. We know that the food of plants consists 

 of not-living or so-called mineral ingredients, we 

 know also that the plant grows, and therefore that 

 these non-living ingredients must be decomposed 

 in order to give place to the new living matter 

 which is continually being produced. Physical forces 

 and natural affinities are, therefore, supposed to be the 



