210 Atkinson. 



trast characters, the majority of which under normal culture are so 

 clear cut and strikingly different in the two parents, permits a very 

 satisfactory analysis of the transmission of the characters to the pro- 

 geny, as well as their composition in the Fi hybrids. 



The habit of the plants is shown in figure 1 and 2, all from 

 biennials. In figure 1 are presented nutans and the three hybrid types 

 of the cross nutans X pycnocarpa; nutans takes the first place, the 

 Fl blend (nutella) the second, the green stemmed Fi segregate (pyc- 

 nella) the third, and the red stemmed Fi segregate (tortuosa) the 

 last place. In figure 2 are presented pycnocarpa and the two hybrid 

 types of the reciprocal cross pycnocarpa X nutans: pycnocarpa in the 

 upper left hand corner, the Fi blend (nutella) in the upper right and 

 the Fl segregate (pycnella) in the lower left. 



The habit of the parents is strikingly different, that of the blend 

 (nutella) is rather intermediate, while the habit of the green stemmed 

 segregate (pycnella) is more like that of nutans, and the red stemmed 

 segregate (tortuosa) more like that of pycnocarpa. The conditions under 

 which the two segregates were grown were not very favorable for the 

 development of the habit. In the green stemmed segregate (pycnella) 

 the plants were rather crowded, and also there were a number of 

 rosette branches wMch crowded the branches from the base of the stem 

 and gave them a more strict habit as in pycnocarpa. These rosette 

 branches, which often are as tall as the main stem, were removed be- 

 fore the photographs were taken. They should have been removed 

 when young so that the main stem with its branches would have been 

 free to express the normal habit. In the red stemmed segregate (tor- 

 tuosa) the main stem of all the individuals except one (a small plant) 

 was fasciated so that it did not reach its normal height. The individual 

 represented in figure 1 (last photograph) notwithstanding this condition 

 reaches considerably above the top of the branches. Here the fasciated 

 stem splits into two fasciated ones. 



In figure 3 are presented details of the inflorescence^). The 

 differences in the petal characters are striking. The upper row con- 

 tains nutans at the left, and then follow in order the three hybrid 

 types (nutella, pycnella and tortuosa) when nutans is the mother. The 

 lower row contains pycnocarpa- at the left, and the two hybrid types 

 (nutella and pycnella) when pycnocarpa is the mother. The petals of 



^) It was rather late in the season when the flowers of nutans and pycnella 

 (p X n) were made, and the bracts were not quite so large as the earlier ones. 



