CHAPTER II 

 FACTORS IN EVOLUTION 



PROFESSOR H. F. OSBORN has recently 

 enunciated the law of four inseparable factors 

 that may be denominated the primary processes of 

 evolution. He says : " The life and evolution of or- 

 ganisms continuously center around the processes 

 which we term heredity, ontogeny, environment, 

 and selection. These have been inseparable and in- 

 teracting from the beginning; a change introduced 

 'or initiated through any one of these factors causes 

 a change in all." 



HEREDITY 



Heredity. The transmission of like character- 

 istics from parent to offspring is a sufficiently 

 familiar phenomenon, but the factors directly con- 

 cerned with this are by no means clearly under- 

 stood. It is inconceivable that under any circum- 

 stances an acorn should produce anything but an 

 oak, or that the offspring of a dog should be any- 

 thing but a dog; but why the germ cell of a specific 

 organism should always follow the same course of 

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