320 EVOLUTION, OLD AND NEW. 



cations of the living principle under modification of 

 circumstance? or have they resulted from the com- 

 bined agency of both ? 



" Is there only one living principle 1 Does organized 

 existence, and perhaps all material existence, consist of 

 one Proteus principle of life capable of gradual circum- 

 stance-suited modifications and aggregations without 

 bound, under the solvent or motion-giving principle of 

 heat or light? There is more beauty and unity of 

 design in this continual balancing of life to circum- 

 stance, and greater conformity to those dispositions of 

 nature that are manifest to us, than in total destruc- 

 tion and new creation. It is improbable that much of 

 this diversification is owing to commixture of species 

 nearly allied ; all change by this appears very limited 

 and confined within the bounds of what is called spe- 

 cies ; the progeny of the same parents under great dif- 

 ference of circumstance, might in several generations 

 even become distinct species, incapable of correpro- 

 duetion. 



" The self-regulating adaptive disposition of organ- 

 ized life may, in part, be traced to the extreme fecundity 

 of nature, who, as before stated, has in all the varieties 

 of her offspring a prolific power much beyond (in many 

 cases a thousand fold) what is necessary to fill up the 

 vacancies caused by senile decay. As the field of exist- 

 ence is limited and preoccupied, it is only the hardier, 

 more robust, better suited to circumstance individuals, 

 who are able to struggle forward to maturity, these 

 inhabiting only the situations to which they have 

 superior adaptation and greater power of occupancy 



