OENOTHERA LAMARCKIANA MUT. VELUTINA. 169 



of 0. Lamarckiana are not only externally, but also internally, in 

 the velutina condition. The former, therefore, is to be considered 

 as a pure mutant velutina 1 ). 



I shall now describe the single crosses as briefly as possible. 



0. syrticola x 0. blandina was made on 2 biennial plants of the 

 first named species in July 1913, the pollen of a green blandina 

 being used in the one case, and that of a pale green one in the other 

 case. The seeds of the first one were sown in 1914, those of the other 

 in 1915. Both of them gave cultures of 70 healthy offspring, making 

 a total of 140, of which 25 and 10 specimens were allowed to flower 

 and to ripen their fruits, after the others had been pulled up, in 

 June, before flowering. They were compared in every month of 1914 

 with the twins of 0. syrticola x 0. cana, and in 1915 with those 

 from a cross of 0. syrticola x 0. Lamarckiana, made in 1913 on a 

 specimen of the same group of biennial plants as used for the cross 

 with 0. blandina. All of the 140 hybrids were evidently velutina 

 and exactly like those of the control cultures. 



0. blandina x 0. biennis Chicago. — This cross was made on two 

 specimens of 1913, the pollen of the same parent plant being used 

 in both of them. They gave uniform cultures of 60 and 80 plants, 

 of which 25 and 10 were allowed to make long spikes of flowers and 

 fruits. The others were annual plants also, but were thrown away 

 in June, as soon as they reached a height of 30—40 cm., and showed 

 their marks so as not to leave the least doubt concerning their 

 velutina qualities. In 1914 I compared them with the hybrids of 

 0. cana x 0. biennis Chicago, and in 1915 with those of 0. Lamarck- 

 iana x 0. biennis Chicago, which I cultivated in the first generation 

 as well as in the second, from another cross. The flowering indi- 

 viduals of all these crosses reached, in September, a height of more 

 than 2 m., and all the blandina hybrids were, during all the stages 

 of their evolution, like the velutina of the controlling cross. 



0. blandina x 0. Cocker elli. — Seeds of only one cross of 1913 

 were tried, both parents being annuals. One part was sown in 1914, 

 another in 1915; size of the cultures, 60 + 80 = 140 specimens, of 

 which 25 and 21 flowered. One of the latter was the lata mutant 

 previously mentioned. In June 1914, there was not the least doubt 

 concerning the identity of all the 60 specimens with 0. {cana x 



*) Of course, other combinations, or combinations of the loss of the splitting 

 capacity with other external marks must be admitted to be possible. As a matter 

 of fact, such combinations occur from time to time, as, for example, in 0. oblonga; 

 see Gruppenweise Artbildung, p. 266. 



