686 



MUTANT RACES DERIVED FROM OENOTHERA 



Oenothera semigigas Mut. spathulata. 



Among the mutants of Oe. semigigas x velutina four specimens of 

 spathulata with 15 chromosomes and of a pure type have been recor- 

 ded (de Vries 1924 b, p. 261). They had, however, no good pollen 

 and were therefore fertilized by means of Oe. blandina. This change 



Table 3. 



Oenothera semigigas mut. liquida. Second generation. 



from the ordinary method of self-fertilizing must result in two main 

 changes in the progeny. Instead of specimens of the type of Lamarcki- 

 ana, the well known hybrid Oe. (Lamarckiana x blandina) laeta, 

 must arise, and instead of the barren grains of velutina x velutina, 

 viable seedlings with the characters of Oe. blandina must be found. 

 According to the preferential fertilization of this latter (de Vries 

 1924 a) the blandina plants will occur in relatively too high numbers. 

 There were still some empty grains, reaching 30 to 52 percents of 

 the harvest, but these were evidently due to the weak condition 

 of the type. The offspring of the four mutants flowered for the 

 larger part in 1924 and yielded the figures of table 4. 



Table 4. 

 Oenothera semigigas mut. spathulata after fertilization by Oenothera blandina. 



