706 



BRITTLE RACES OF OENOTHERA LAMARCKIANA. 



were cultivated on a separate bed near to them, in order to compare 

 them in every phase of their development. No laeta plants were 

 found. Only a part of the velutina, however, were exactly like their 

 type, since another part had a broader foliage, the leaves reaching 

 about half the breadth of the corresponding laeta. Table IX gives the 

 results of the countings. 



No brittle plants were found, since this character is recessive. 

 In the first cross the hybrids had the type of laxa, as was to be 

 expected. From table IX it is evident that tarda is isogamic, the 

 reciprocal crosses giving the same result, and has two kinds of gametes 

 in about equal numbers, corroborating the formula given. The 

 difference between these two kinds of gametes, however, is much 

 smaller than that between the gametes of either scindens or Lamarck- 

 iana, almost all of their characters belonging to the category of 

 velutina. This is corroborated by the results of other crosses. 0. 

 tarda x elongata gave an almost uniform progeny of the type of 

 Lamar ckiana. Elongata is a laeta type, with uniform pollen, and must 

 give with the pallida the combination velutina x laeta, since the 

 brittleness is recessive. There were 6 per cent of barren seeds and 

 some mutants. 



0. tarda x tardescens produced a dimorphic progeny with some 

 mutants, which, however, did not flower. Among the 51 flowering 

 individuals, 39 showed the marks of tarda and 12 those of pallida. 



Table IX. 

 Crosses of O. tarda with other species. 



0. tardescens has only velutina gametes in its pollen, and their special 

 marks were evidently recessive to those of the components of 0. 

 tarda. 



