CHAPTER XII 



(ENOTHERA AND THE MUTATION 



THEORY 



The mutation theory was first developed by 

 deVries on the basis of his extensive experiments 

 with the Evening Primrose, CEnothera Lamarckiana. 

 This plant was found growing wild at Hilversum, 

 near Amsterdam, in Holland. DeVries noticed that 

 several aberrant types were growing with the 

 typical form, and when he planted in his garden 

 self-fertilized seed from Lamarckiana (the typical 

 form) he found that these other types reappeared 

 in small numbers, a,nd continued to do so year after 

 year and generation after generation. Most of the 

 new types themselves bred true with the exception 

 that they also gave a few aberrant types in the 

 same way as Lamarckiana. The following table 

 shows the percentages of certain types obtained 

 from Lamarckiana and from some of the new types 

 themselves. 



Soon after the rediscovery of Mendel's work 

 (1900) the data that were rapidly collected regard- 

 ing the genetic behavior of many different animals 

 and plants made it evident that CEnothera was 

 unique in its behavior in many other ways than in 

 the relatively great frequency with which it pro- 

 duces new types. This led Bateson and Saunders, 



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