

1917] DEVRIES— OENOTHERA 7 



In 191 2 I saved the seeds of 4 self- fertilized plants separately. 

 Two of them had been green from their first youth and the two 

 others had been of a pale color in the beginning. The result was, 

 in 1 9 13, a small but distinct advantage of the two first sowings over 

 the two latter sowings. I have chosen the first ones for the crosses 

 to be described later on, and repeated this third generation in 19 14 

 in order to give the plants more space and a better manured soil, 

 and to compare such vigorous individuals with others growing in 

 a dry and poor soil. The results of this comparison have been 

 described elsewhere; they showed that the seeds produced by the 

 two groups were different. Almost all the seeds of the strong plants 

 contained a healthy germ, but among the seeds of the weaker indi- 

 viduals there were about 25 per cent of empty ones. The germi- 

 nation showed even a larger difference, giving about 80-90 per 

 cent of seedlings for the normal seeds and only about 50 per cent 

 for those of the weaker plants. 3 I shall return to this phenomenon 

 in the second part of this article. 



The fifth generation was derived, in 191 5, from seeds of 4 self- 

 fertilized individuals of 19 14, chosen as the best ones among the 

 stronger of the two groups. Sixty plants from one parent were 

 planted in my experimental garden on good soil and with plenty 

 of space, in order to be used for crosses. The remainder embraced 

 about 3000 plants (between 600 and 800 from each parent) and 

 were set out in another garden in order that the degree of muta- 

 bility of this race might be studied. It was found to be rather 

 small, although almost all of these plants have flowered and have 

 been carefully tried at different stages of their evolution, from 

 their germination to the time when their last flowers faded away in 

 August and their first fruits ripened. 



The result of these repeated inspections has been that 4 mutants, 

 belonging to one type, were discovered, but that no other deviation 

 could be observed. This gives a percentage figure of o . 1 . If we 

 compare this with the table given on p. 337 of my Gruppenweise 

 Artbildung, we see that 0. blandina falls into the group of those 

 mutants (O. nanella and O. rubrinervis) , the mutability of which has 



3 Uber kiinstliche Beschleunigung der Wasseraufnahme in Samen durch Druck. 

 Biol. Centralbl. 35:175. 1915. In this article O. blandina has been provisionally 

 designated as O. Lamarckiana mut. nov. B. 



