104 NEW DIMORPHIC MUTANTS OF THE OENOTHERAS. 



father. 1 ) The comparison embraced the whole lifetime from the 

 germination in February until the production of the fruits in Sep- 

 tember. No differences have been observed. 



From table XII we see that the splitting percentages are 

 practically the same, whether the pollen is taken from 0. biennis 

 Chicago, 0. Cockerelli or 0. Hookeri. For this reason I have given 

 the mean for each group in the last columns of the table, and the 

 reliability of this mean evidently depends strongly on this fact. 



Theoretically a splitting into 4 groups of equal size should be 

 expected, namely into cana-laeta, cana-velutina, laeta and velutina. 2 ) 

 Evidently one of the first two groups is suppressed. This con- 

 clusion holds good for 0. cana just as for 0. scintillans, but in the 

 case of 0. lata the fourth group is sometimes visible, a few speci- 

 mens of the /ata-like hybrids assuming at the same time the marks 

 of 0. laeta (about 1 per cent, Gruppenweise Artbildung, p. 255), 

 whereas the remainder are clearly lata-velutina. It is probable 

 that the same group is suppressed in both the other cases, and for 

 the same reasons, which are as yet unknown. The fact that there 

 are so often more velutina than should be expected probably has 

 the same cause as the exuberant occurrence of this form in the 

 crosses of 0. Lamarckiana (82 per cent). The analogous crosses 

 of 0. nanella, given in the lower part of the table, show that these 

 diminutions of the laeta type may, at least in part, be considered 

 as influenced by neighboring characters. The combination 0. cana 

 nanella has occurred in many instances during these experiments, 

 either from the crosses of 0. cana with the dwarfs of my race, or 

 as occasional mutations in other cases. A repetition of my experiments, 

 in which 0. cana nanella would be chosen for fertilization by the 

 other species or mutants used, would probably give the material 

 to decide these questions. 



Putting aside all of these more special considerations, we may 

 conclude that 0. cana behaves in its crosses, as well as after self- 

 fertilization, exactly after the manner of 0. scintillans and 0. lata. 

 From this fact and from the cross Lamarckiana x pallescens, pre- 

 viously mentioned, it seems probable that the other new dimorphic 

 mutants, namely 0. pallescens, 0. liquida and 0. Lactuca, will 

 follow the same rule if tried in the same way. This rule is evi- 

 dently independent of the external types of their characters, but 



i) On twin hybrids. Opera VI, p. 472. 

 2) On triple hybrids. Opera VI, p. 496. 



