David Starr Jordan 



the Crawford. A cross of the nectarine and peach 

 also produces variant types of value. In some 

 hybrids of petunia and tobacco, the roots fail 

 while the tops may be of unusual vigor. These 

 individuals can only be kept alive for any length 

 of time by grafting, another instance — if other 

 were needed — of the parallelism of crossing and 

 grafting. 



character may be latent through many 

 generations or centuries, appearing when the right 

 cross brings it out, or it may appear under espe- 

 cially favorable or peculiar conditions of growth.'* 

 The essential of Burbank's method may be 

 here briefly restated. In the formation of all 

 races or breeds of animals or plants we may have 

 the following stages : — 



1. Unconscious selection with more or less 

 complete isolation of the chosen forms. 



2. Conscious selection of the most desirable 

 individuals. 



3. Conscious selection directed towards definite 

 or special ends. 



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