NATURAL SELECTION 155 



Heredity limits the range of variation unless there is reversion 

 and this can proceed far, only through the adoption of a parasitic 

 life or by retirement to sequestered regions where the stress of 

 competition is less. But heredity governs the environment no 

 less ; for the important factors in the environment are, as a rule, 

 the competing species and these have been evolved pari passu with 

 that one whose evolution we are considering. Thus in the matter 

 of variations the field of chance is limited, nor is it an utterly 

 chance environment with which the adaptation has to be effected. 

 There are limits on either side, but within these limits chance 

 has free play: an adaptation is a coincidence. Nor is there, 

 apart from selection, a definite tendency. It is true that it has 

 been found by breeders and gardeners, that if a variation appears 

 and is preserved by selection, greater variations in the same 

 direction are likely soon to show themselves. But there is 

 nothing antagonistic to Darwinism in this. At every step selec- 

 tion must clinch the new development. It follows from this 

 that mere isolation could not, by allowing a fair field to an 

 incipient variety, bring about much further evolution. 



Often alternative environments offer themselves, and this makes 

 the coincidence on which adaptation depends comparatively easy. 

 A species of plant may come into rapport with the wind or birds 

 or mammals, hence the variety of the modes of fertilisation and 

 of transporting seeds. 



The further specialisation has proceeded, the narrower has be- 

 come the range within which chance has been allowed to operate. 



The problem of the origin of consciousness puts us on the 

 horns of a dilemma. Either consciousness is present in the 

 lowest forms of life or else it was introduced at a higher stage 

 of development. The latter alternative is abhorrent to the very 

 principle of evolution. We are driven, then, to believe that 

 even the micro-organisms whether animal or vegetable have 

 some consciousness, however dim. 



Lastly, Natural Selection is only a regulating principle, not 

 a force ; it has but guided the evolution of living organisms. 

 Logic compels the evolutionist to assume a force that was not 

 evolved, but which existed before evolution began. 



