44 



Mutations and Evolution. 



obtained mut. lata from an (E. biennis race, also a red-nerved (rubri- 

 nervis type and a Icevifolia. Stomps (1912a), in the cross (E. biennis 

 X (E. biennis leptomeres Bartl. (leptomeres=(E. biennis cruciata 

 de Vries) observed one dwarf mutant (biennis nanella) and one 

 sonigigas (with 21 chromosomes). The biennis parent was 

 descended from a rosette collected by Stomps on the sand dunes 

 near Wykaan-Zee in 1905, which gave a uniform race. The biennis 

 leptomeres was derived from a plant originally collected in 1900 by 

 Ernst de Vries near Santpoort, Holland, and from which a constant 

 strain was obtained. In 1903, one dwarf ((E. biennis leptomeres 

 nanella) arose in about 600 of the tall cruciate variety. The 

 original leptomeres plant, when found in 1900, was surrounded by 

 a number of normal biennis, and evidently had arisen as a mutation. 



TABLE II. 

 PARALLEL MUTATIONS IN QINOTHERA. 



The significance of the various species and varieties with 

 cruciate flowers will be considered later. The first experiments 

 with pure CE. biennis were undertaken by Stomps (1914). He 

 collected a rosette of this species at Beverwyk, Holland, in 1905, 

 from which he obtained a pure line. Among over 900 plants 

 belonging to the third and fourth generations, Stomps found 6 

 mutants, 1 nanella, 1 semigigas and 4 sulfurea. The last differs from 



1 When enclosed in parentheses, the form is a presumptive mutation, but 

 has not actually been obtained in a pedigree culture. 



1 For a description of this "species," probably of hybrid origin, see 

 Gates, 1914b. 



* Davis, 1913. 



