Theories of Evolution 27 



sown. Cultivated plants of course, had only 

 a small chance to exhibit new qualities, as they 

 have been so strictly controlled during so many 

 years. Moreover their purity of origin is in 

 many cases doubtful. Among the wild plants 

 only those could be expected to reward the in- 

 vestigator which were of easy cultivation. For 

 this reason I have limited myself to the trial of 

 wild plants of Holland, and have had the good 

 fortune to find among them at least one species 

 in a state of mutability. It was not really a 

 native plant, but one probably introduced from 

 America or at least belonging to an American 

 genus. It was the great evening-primrose or 

 the primrose of Lamarck. A strain of this 

 beautiful species is growing on an abandoned 

 field in the vicinity of Hilversum, at a short dis- 

 tance from Amsterdam. Here it has escaped 

 from a park, and multiplied. In doing so it has 

 produced, and is still producing quite a number 

 of new types, some of which may be considered 

 as retrograde varieties, while others evidently 

 are of the nature of progressive elementary 

 species. 



This interesting plant has afforded me the 

 means of observing directly how new species 

 originate, and of studying the laws of these 

 changes. My researches have followed a double 

 line of inquiry. On one side, I have limited 



