i9i 7] DeVRIES— OENOTHERA 13 



Crosses of O. blandina with O. Lamarckiana. — If the laeta 



qualities have become latent and inactive in O. blandina, we should 

 expect that this mutant would have acquired the property of 

 splitting itself these qualities in O. Lamarckiana. The confirma- 



xpectation must 



from 



mutants 



may give rise to the same hybrid twins as the parent species, we 

 may expect O. blandina to split them also. I made both the 

 reciprocal crosses with the parent species and one with the dwarf, 

 and all 3 cases have corroborated my conception. I made the 

 crosses in 19 13 in the third generation of my race, and cultivated 

 the first generation in 19 14, repeating it in 1915. The splitting 

 occurred in all 3 cases as expected, giving nearly equal groups of 

 the two types. One of these types exactly corresponded to O. 

 blandina itself; in comparing it from its first youth up to the time 

 of flowering and fruiting, I could not discover any difference. 

 This one should be considered as the velutina, therefore, and will 

 be called 0. (Lamar ckianaX. blandina) velutina a.s.o. The other 

 type was evidently a laeta. During some stages of its evolution 

 it was almost wholly like O. Lamarckiana, but later it changed its 

 appearance and displayed some of the characters which usually 

 distinguish the different forms of the hybrid laeta from their parents. 

 For this reason I shall call it O. (LamarckianaXblandina) laeta, or 

 briefly O. blandina laeta, implying by this name only the presence 

 of one or more characteristics of the laeta type, but not necessarily 

 all of them. 



According to the species which determine the splitting in 

 O. Lamarckiana, the types of hybrid laeta may be divided into two 

 groups. One of them is small-flowered and ordinarily tall, corre- 

 sponding to the rigida type described and figured in my book 

 (PP- 73, 80, 81). To this type appertain the laeta produced by 

 O. biennis, O. muricata, 0. Cockerelli, and 0. biennis Chicago. The 



typ 



embraces only the O. (H 



Lamarckiana) laeta and its reciprocal. The flowers have the same 



size in both parents, and therefore this size is not changed in the 

 hybrids. In the cross of O. Lamarckiana and O. blandina the same 

 rule prevails, the flowers of the hybrid being not rarely even some- 

 what stouter than those of the parents. 





