LUTHER BURBANK 



Professor de Vries' celebrated evening primroses 

 had the same origin. It is true that the parent 

 form was not known to be hybridized, and that 

 there was no known form of evening primrose 

 at hand through which hybridization could have 

 taken place. 



But the precise origin of the original plants 

 found near Amsterdam is entirely unknown; and 

 the curious conformity of their offspring, under 

 Professor de Vries' observation, to the habitual 

 variation of hybrid races in the third and subse- 

 quent generations is so pronounced that it cannot 

 well escape the observation of anyone who has 

 had large experience with such races. 



This fact was at first overlooked by most 

 biologists, largely because they lacked such 

 experience. But now there is a growing tendency 

 to take this view of the case. 



Attempts have even been made in very recent 

 years to produce a similar series of mutational 

 forms of evening primrose by direct hybridization 

 of existing forms. And while the results have not 

 been absolutely definitive, they are unquestionably 

 suggestive; and there is without doubt a growing 

 appreciation of the fact that plants may be made 

 to take on the notable changes which we described 

 as mutations by the hybridizing of allied races; 

 and that this explanation of the origin of mutation 



[98] 



