ATKINSON— TWIN HYBRIDS. 137 



long by 3 cm. broad. The calyx buds are 3-3.5 cm. long by 7-8 

 mm. broad at the base, tapering gradually to the apex, usually an 

 abundance of red color in the calyx, sometimes with only a faint 

 tinge. The open flowers are 4.5-5 cm. broad, the petals narrowly 

 obovate to cuneate with gaps between them at the base, 20-25 mm. 

 long and broad in the larger flowers. The stamens do not quite 

 reach the base of the stigma, and the stigmas are more slender and 

 longer than in the pycnocarpa type. The flowers are more delicate 

 and wilt earlier than those of the pycnocarpa type. Pods 4-4.5 cm. 

 long by 7 mm. stout at the base. The leaves are exactly like those 

 of the parent franciscana, narrow, long, only slightly furrowed, 

 toothed on the edges, not so drooping as in the pycnocarpa type, plane, 

 midvein white, foliage pale green contrasting strongly with the dark 

 green foliage of the pycnocarpa type. 



The fruiting spikes in these annual F^ cultures also show a dis- 

 tinct splitting into two types in regard to the length of the spike or 

 fruiting axis. 



CEnothera franciscana y^ pycnocarpa (No. loi). — The reciprocal 

 cross, CEnothera franciscana X pycnocarpa gives also a F^ progeny 

 which splits into two hybrid types. These types are identical with 

 those just described from the cross pycnocarpa X franciscana. 

 There were 102 plants of the F^, 90 of these belong to the francis- 

 cana type and 12 to the pycnocarpa type. Here as in the reciprocal 

 cross a preponderance of the progeny is of the franciscana type. 



The Fo Generations. 



From the F^ progeny of the crosses between CEnothera francis- 

 cana and pycnocarpa, seed was saved and sown from three of the 

 hybrid types, the pycnocarpa type, and franciscana type of twin from 

 the Fi of (E. pycnocarpa X franciscana; and from the pycnocarpa 

 type of twin in the reciprocal cross. The cultures were carried 

 along parallel with those of the F, described above, from crosses 

 between CE. lamarckiana and pycnocarpa. They were grown as 

 biennials, and the rosettes were mature and fully developed in the 

 autumn of 1916. 



Pycnocarpa type F, No. i^y (pycno Xf ran). —There were 50 



