HEREDITY 195 



that is needed to break down this weak apparent stability of the 

 type and allow its component characters (the elementary units 

 of de Vries) to recombine into various new and differing types. 

 This condition seems to be that which results in the extraordi- 

 nary variation so commonly observed by plant and animal 

 breeders as brought out by hybridization, and which is con- 

 stantly made use of by these breeders. Luther Burbank de- 

 pends very largely on this initial abundant and eccentric varia- 

 tion induced by wide hybridizations for " starters " for his work 

 of producing "new creations." 



So in accepting Mendel's laws of heredity we must bear 

 clearly in mind that they by no means apply to all, or, at any 

 rate, that our present knowledge of them does not include their 

 application to all, cases and categories of inheritance. 



