534 



STRUCTURE AND LIFE HISTORIES 



Latnarckiana their cordate character. I call this form 

 0. IcBvifolia." 



"When I first discovered them (1887) they were repre- 

 sented by very few individuals. Moreover each form 

 occupied a particular spot on the field. 0. brevistylis 

 occurred quite close to the base from which the QEnothera 



Fig. 400. — A plant of the evening-primrose {(Enolhcra biennis) which 

 by "bud sporting," has given rise (at the left) to a branch having the 

 characters of another species. (Photo by the author.) 



had spread; 0. IcevifoUa on the other hand, in a small 

 group of 10 to 12 plants, some of which were flowering 

 whilst others consisted only of radical leaves, in a part of 

 the field which had not up to that time been occupied by 

 O. Lamarckiana. The impression produced was that all 

 these plants had come from the seeds of a single mutant. 

 Since that time, both the new forms have more or less 

 spread over the field" {de Vries). 



