32 THE ORIGIN OF LIFE 



others that may show merely a cyclic change without 

 metabolism, or simply metabolism without a cyclic 

 change ? The former might still come under Herbert 

 Spencer's definition ; the latter may not strictly 

 speaking do so. 



And yet if there is a continuous change of sub- 

 stance together with that integration and disintegra- 

 tion which we call metabolism : are we or are we not 

 justified in regarding this as some elementary or 

 primitive form of life ? 



The atoms of radio-active bodies are such sub- 

 tances, and if they are found, by acting as a nucleus, 

 as they have been found to give rise to more 

 complex forms in organic substances, forms which 

 undergo the cyclic changes and adjust themselves to 

 their environments by internal and external inter- 

 changes, they then come under some definition of life 

 in a higher sense ; and would, I think, be regarded, 

 and very rightly so, as elementary types of life. This 

 may seem highly heterodox, but, for aught we know, 

 may be true. 



Life in its very simplest sense would consist of 

 metabolic processes and catalytic actions such as those 

 that occur not merely in radioactive bodies, but in 

 phosphorescent and luminous bodies generally. 



Thus does there appear to be a continuity of vital 

 actions, a gradual dropping off of properties and 

 simplification of the process as we descend from 

 higher organisms to smaller things down to the very 

 atom itself ; and vice versd a gradually increasing com- 

 plexity as we mount the scale of being, with an 



