THE EVOLUTION PROCESS 247 



which first makes the mammal, and then 

 marks each of its distinctive upKfts of further 

 progress (from monotreme to marsupial, 

 and thence to placental), that increase of 

 parental care, that frequent appearance of 

 sociality and co-operation which, even in its 

 rudest forms, so surely secures the success 

 of the species attaining it, be it mammal or 

 bird, insect or even worm — all these survivals 

 of the truly fittest, through love and sacri- 

 fice, sociability and co-operation simple to 

 complex — need far other prominence than 

 they can possibly receive even by some mil- 

 dewing attenuation of the classic economic 

 hypothesis of the progress of the species 

 essentially through the internecine struggle 

 among its individuals at the margin of 

 subsistence. 



Our theory thus furnishes a re-interpreta- 

 tion of the forms attained by plants and 

 animals comparable to that afforded by the 

 received hypothesis (and, if space allowed, 

 traceable into no less refinement of detail), 

 yet with an essentially allied view of the 

 process and factors of organic evolution as a 

 whole. Most briefly stated, the view of evo- 

 lution thus reached is that of definite varia- 

 tion: its branchings essentially dichotomous 

 rather than indefinite, with progress essen- 

 tially through the subordination of individual 



