386 



EVOLUTION, GENETICS, AND EUGENICS 



variation within the species. Darwin depended upon it as the basis of 

 his theory of natural selection as the origin of species; in fact, ever 



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Fig. 76. — Diagram illustrating Nilsson-Ehle's 63:1 ratio. (From Coulter 

 and Coulter.) 



since Darwin's Origin of Species, individual variation has been funda- 

 mental in our conceptions. To account for this universally recog- 

 nized phenomenon, Darwin proposed his transportation hypothesis as 



