2i8 HOLISM AND EVOLUTION chap. 



they bear on the wide Darwinian conception from which 

 we started. 



The relative importance of the internal and external 

 factors in Evolution has materially altered since Darwin's 

 time. Variation has become much more important than 

 Natural Selection, not only in biological studies and experi- 

 mental researches, but also in our view of it as an operative 

 factor in organic Evolution. While remaining a substantial 

 and important factor Natural Selection has yielded pride 

 of place to Variation. The factor of intense struggle and 

 competition in Nature on which Darwin, following the 

 Malthusian clue, laid so much stress is now seen not only 

 to have less importance relatively, but also to bear a some- 

 what different character from what it had in Darwin's view. 

 The struggle for existence is, like Mutation, an exceptional 

 and not the usual procedure of organic Nature. This 

 world is at bottom a friendly universe, in which organised 

 tolerant co-existence is the rule and destructive warfare 

 the exception, resorted to only when the balance of Nature 

 is seriously disturbed. Normally Natural Selection takes 

 the form of comradeship, of social co-operation and mu- 

 tual help. Normally also the organic struggle is very 

 much in abeyance, and the silent, effortless, constant pres- 

 sure of the physical and organic environment exercises a 

 very powerful influence. The young science of Ecology 

 has been built up since Darwin's time and is based on 

 the recognition of this fact, that, in addition to the opera- 

 tion of Natural Selection, the environment has a silent, 

 assimilative, transformative influence of a very profound 

 and enduring character on all organic life. In the subtle 

 ways of Nature, sun and earth, night and day, and all the 

 things of earth and air and sea mingle silently with life, 

 sink into it and become part of its structure. And in re- 

 sponse to this profound stimulus life grows and evolves, 

 the lesser whole in harmony with the greater whole of 

 Nature. 



The interaction between the inner and the outer factors 

 in Evolution is far more close and subtle than one would 



