80 GENETICS AND EUGENICS 



about the year 1860 may have come from some English lo- 

 cality. The fact that several species of Oenothera are known 

 to have been in England previous to this date suggests that 

 Lamarckiana may have arisen through the crossing of other 



forms. 



In this connection it is of interest to note that a hybrid 

 has been synthesized by Davis from a cross of . franciscana 

 with 0, biennis, which is essentially indistinguishable in its sys- 

 tematic characters from 0. Lamarckiana. Furthermore this 

 hybrid behaves like Lamarckiana in producing two classes of 

 progeny when crossed with certain wild species as described 

 in the next paragraph. This Lamarckiana-\\ke hybrid, 

 which has been given the name of neo-Lamarckiana, in the 

 fourth generation bred true for about one-third of its pro- 

 geny and therefore gave a very much larger percentage of 

 variants than Lamarckiana, but its seed fertility was very 

 much higher, which may account for the fact. At this stage 

 in the investigation neo-Lamarckiana presents a breeding 

 behavior at least similar to that of Lamarckiana and it will 

 be a matter of interest to see whether in later generations the 

 resemblance may not become more marked. 



Another adverse view of De Vries' theory, with less concern 

 as to the origin of 0. Lamarckiana, maintains that however it 

 originated it is clearly not pure genetically; if not actually a 

 hybrid of recent origin, it at least has the genetic character of 

 a hybrid and hence the regularity of its mutations. For hy- 

 bridization, as we shall see, is a sure means of producing new 

 and stable varieties. Hybridization experiments made by 

 De Vries and repeatedly confirmed by others show that in 

 every generation 0. Lamarckiana produces different kinds of 

 fertile gametes. In particular, it forms two classes of hy- 

 brids, " twin hybrids," in approximately equal numbers, in 

 crosses with certain wild species, as do several of the wild 

 species in crosses with each other, so that it is evident that 

 0. Lamarckiana, as well as some wild species of Oenothera, 

 have the variability characteristic of hybrids. Even those 

 which seem to breed true, and which do breed true when 



