MUTATIONS 



277 



a species in which the transformation into new forms was proceeding 

 on a scale large enough to make possible the direct observation of species 

 formation. In none of the particular races that he collected did he 

 observe profound discontinuous variations until in 1886 he discovered 

 a feral group of large-flowered evening primroses (CEnothera lamarckiand) 

 growing in a suburb of Amsterdam. They had escaped into an abandoned 

 potato field from a nearby park. The source of this particular even- 

 ing primrose has been traced by de Vries. About the middle of the 19th 



FIG. 114. CEnothera lamarckiana. 



(From a painting. See de Vries, Gruppcnweise Art- 

 bUdung.) 



century seeds of GE. lamarckiana were imported into England from Texas. 

 De Vries' race came from an estate near Hilversum, the seed having 

 been obtained originally from an establishment in Erfurt, which de 

 Vries thinks must have obtained their seed from England. It has never 

 been found as an indigenous species either in Europe or America. This 

 beautiful plant is much prized as an ornamental and is known to have 

 escaped from cultivation in various places. 



"Lamarsk's evening primrose is a stately plant, with a stout stem, attaining 

 often a height of 1.6 meters and more (see Fig. 114). When not crowded the 

 main stem is surrounded by a large circle of smaller branches, growing upward 



