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TEXTBOOK OF BOTANY 



Plate 7. The red sunflower, a mutant from the common yellow-flowered ancestor 



(Helianthus anninis) . 



idea that environment is responsible for about everything a hving or- 

 ganism does, it appears, on the basis of experimental evidence, that the 

 causes of mutations are wholly or mainly intrinsic. The effects of the 

 environmental factors appear to be limited largely to changes in the rates 

 of mutation rather than changes in the kinds of mutation. 



Perhaps the popular belief in the omnipotence of the environment is 



