THE BEGINNINGS OF LIFE. 75 



the subject we shall subsequently allude more in detail. 

 We must, however, now call attention to a very im- 

 portant essay by Mr. G. H. Lewes 1, in which he promi- 

 nently develops those aspects of the doctrine which pre- 

 viously had not been sufficiently elucidated. He dwells 

 upon the extreme importance of variation or similarity 

 in external conditions in inducing living things (in 

 which ^we observe such a community of elementary 

 substance') to vary or resemble one another in their 

 organic forms. In one passage he says ^ : — ^ Although . 

 observation reveals that the bond of kinship does 

 really unite many divergent forms, and the principle of 

 Descent with Natural Selection will account for many 

 of the resemblances and differences, there is at present 

 no warrant for assuming that all resemblances and 

 differences are due to this one cause, but, on the 

 contrary, we are justified in assuming a deeper principle 

 which may be thus formulated : All the complex 

 organisms are evolved from organisms less complex, as 

 these were evolved from simpler forms : the link which 

 unites all organisms is not always the common bond of 

 heritage, but the uniformity of organic laws acting under 



uniform conditions It is therefore consistent with 



the hypothesis of evolution to admit a variety of 

 origins or starting-points.' In this^ paper the immense 



from their own structures and actions only, but as the product of these 

 and the environing forces to which they are exposed.' 



^ ' Darwin's Hypotheses,' in Fortnightly Review, 1868. 



^ Loc. cit., p. 370. 



