LUTHER BURBANK 



vogue in Darwin's time, and the idea of evolution 

 through such marked departures from the normal 

 was subordinated, in Darwin's interpretation of 

 the origin of species, or at least in that of his 

 immediate followers, to the idea of advance 

 through the preservation of slight variations. 



So when, just at the close of the nineteenth 

 century. Professor Hugo de Vries came forward 

 with his "mutation theory," it had all the force of 

 a new doctrine, and was even thought by some 

 enthusiasts — though not by its originator — to be 

 in conflict with the chief Darwinian doctrines. 



The observations that led Professor de Vries 

 to the development of this theory were made on a 

 familiar American plant that had found its way 

 to Europe and was growing in profusion by the 

 roadside near Amsterdam. The plant is known 

 as the evening primrose. 



Professor de Vries noted a hitherto unde- 

 scribed variety of this plant in a field near 

 Amsterdam. He took specimens of the plant to 

 his famous experimental gardens and carefully 

 watched the development of successive genera- 

 tions of seedlings. 



To his astonishment he produced in the course 

 of a few generations more than a dozen divergent 

 types of evening primrose, all descended from the 

 original plant, each of which bred true to the new 



[90] 



