SUMMARY OF EVOLUTION THEORIES. 



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of modification. Heredity and variability being given, the 

 whole theory of organic evolution becomes a theory of the 

 causes and conditions which lead to isolation." 



SUMMARY OF EVOLUTION THEORIES. 



(Axiom or Truism). 



Variations are all ultimately due to the External Influences 



and the Nature of the Organism, i.e., of Protoplasm. 



