200 



GENEKAL BOTANY 



variations has been brought into prominence in recent years 

 through the publications of the great Dutch botanist, Hugo de 

 Vries. De Vries first noticed some mutants of the evening 

 primrose known as Lamarck's evening primrose {(Enothera 

 lamarckiana) (Fig. 109) growing in a waste field near Hilver- 



sum in Holland. In 1886 

 he collected seeds from 

 the mother plant and from 

 the two new varieties pro- 

 duced from it by muta- 

 tion, and sowed them in 

 the botanic gardens at 

 Amsterdam. He has since 

 carried on extensive cul- 

 ture experiments with the 

 primroses and their off- 

 spring, and has succeeded 

 in producing several new 

 varieties which differ from 

 the original mother plant 

 in all of the various or- 

 gans of the plant body. 

 One is a dwarf species 

 (Fig. 110), while another 

 is a giant form with 

 greater vegetative vigor 

 and larger flowers than 

 the mother plant. Others 

 vary in the form and 

 color of the leaves, in the character of the seedlings (Fig. Ill), 

 and in the nature of the reproductive organs, including both 

 the flower and the fruit. Since all of these new primroses 

 came suddenly, by one large variation or mutation, and have 

 bred true to seed, De Vries believes that they indicate the 

 way in which other cultivated and wild varieties have arisen 

 whose history indicates a similar method of production. This 

 sudden origin of cultivated forms is well illustrated by the 



FIG. 110. CEnothera lamarckiana and two of 

 its mutants, (E. lata and (E. nanella 



(E. lamarckiana in the middle; lata at the left; 



and nanella at the right. From Babcock and 



Clausen's " Genetics in Relation to Agriculture." 



After De Vries 



