THE MELTING-POT 93 



and partly as seeds from the potato-field at 

 Hilversum to the botanic garden at Amsterdam. 



" The three stocks gave rise under cultivation 

 to many thousands of individuals, which bred true 

 along certain lines, and yet gave rise to other 

 new forms. In short, De Vries had found a plant 

 in the process of evolution. 



"The predisposition to mutability which re- 

 mains a mystery was present. De Vries gave 

 it scope, and like the primeval gardener he had 

 the pleasure of giving names to a crop of new 

 creations which emerged before him. From each 

 of these three samples there arose distinctive 

 groups which, if they had been found in nature, 

 would have been reckoned as distinct species of 

 evening primrose. But the most interesting 

 feature was the apparent abruptness in the origin 

 of the new forms. They seemed to rise by leaps 

 and bounds, by organic jerks ; they illustrated 

 what De Vries has called ' mutation.' " 



It does not concern us here whether De 

 Vries's mutations were the result of a new en- 

 vironment or of some other cause. The point 

 for us is that while there may be variation in 

 the Darwinian sense, there are also sudden 

 changes when animals of different characters are 

 bred together, and under certain circumstances 

 these changes are inherited. Mendel's theory 

 explains both the changes and their inheritance. 

 Mendel's original experiments were made with 



