Scientific Aspects of Luther Burbank V Work 



are inherited .or I know nothing of plant life/ he 

 says; and also convinced that the only unit in 

 organic nature is the individual, not the species; 

 that the so-called species are wholly mutable and 

 dependent for their apparent fixity solely on the 

 length of time through which their so-called 

 phyletic characters have been ontogenetically re- 

 peated. He does not agree at all with de Vries 

 that mutations in plants occur only at certain peri- 

 odic times in the history of the species, but rather 

 that, if they occur at all, they do so whenever the 

 special stimulus derived from unusual nutrition or 

 general environment can be brought to bear on 

 them. He finds in his breeding work no prepo- 

 tency of either sex as such in inheritance, though 

 any character or group of characters may be pre- 

 potent in either sex. He believes that no sharp 

 line can be drawn between the fluctuating or so- 

 called Darwinian variations and those less usual, 

 large, discontinuous ones called sports. Ordinary 

 fluctuating variation goes on under ordinary con- 

 ditions of nutrition, but with extraordinary envir- 



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