Mutations 



61 



found no appreciable change in them, although he watched 

 them for more than forty years. 



Lamark's evening-primrose is grown in Europe as a cul- 

 tivated plant, used principally for ornamental planting. 

 It seeds abundantly and some of the plants have escaped 

 cultivation. Groups of plants are found growing wild 

 in many places. These wild plants remain in groups 

 rather than being widely scattered, suggesting a definite 



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FIG. 18. (Enothera Lamarkiana. Curve exhibiting variations in the 

 length of fruits of 568 plants. The dotted line is that given by 

 Quetelet-Galton Law. 



origin for each group. CE. Lamarkiana is described as a 

 "stately plant with a stout stem, attaining often a height 

 of 1.6 meters and more. When not crowded, the main 

 stem is surrounded by a large circle of smaller branches, 

 growing upwards from its base so as often to form a dense 

 bush. These branches in their turn have numerous 

 lateral branches. Most of them are crowded with flowers 

 in summer, which regularly succeed each other, leaving 

 behind them long spikes of young fruits. The flowers are 



