THE FRAGRANT CALLA 81 



roses 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 prim- 

 rose 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's observation, to the habitual 

 variation of hybrid races in the second and 

 subsequent generations is so pronounced that 

 it cannot w r ell escape the observation of any- 

 one who has had large experience with such 

 races. 



This fact was at first overlooked by most biolo- 

 gists, largely because they lacked such experi- 

 ence. 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 unquestion- 

 ably suggestive; and there is without doubt a 

 growing appreciation of the fact that plants may 

 be made to take on the notable changes which are 

 described as mutations by the hybridizing of 

 allied races; and that this explanation of the 



