CROSSINGS IN MELANIUM-VIOLKTS 279 



THE INHERITANCE OF THE GROWTH FORM. 



In Mcldniiiiu xiolcls (lilTcrriil ^'lowtii iorins occur. In one typ»', 

 which may he the most common one, it is |)ossihlt' to (hstint;iiish main 

 axis and ai)out .') — 6 largi' l)rancht's proceeding Irom the liasis ol 

 the axis near the ground and growing straight upward;». To this type, 

 schematically drawn in tig. 3 A (p. 255), the lines 2, 10 and 13 belong. 

 V. Munbydiui, V. splendida and many, perhaps all, pansies belong also 

 to this type. Anotiier type (li) has the branches pressed to the ground. 

 When the plant is rather young one ol the branches is a little thicker 

 than the others. This branch corresponds presumably to the main 

 axis ol the first type. When the plant l)ecomes older it is not pos- 

 sible to distinguish this branch from the other branches. The lines 

 3, 4 and 5 belong to this latter type. 



Figure 3 D shows a type which has the main axis in an errect 

 grow-position and the l)ranches in a horizontal. I have grown one 

 line (35) of this type. Another type is shown in figure 3 /:. The 

 main axis take nj) a slanting position; the branches are horizontal 

 (line 12). These two pure lines belong both to V. rirvensis, and both 

 bred true. I have not used them for crossings, however. 



I have only grown the F:.-generation of one cross between diffe- 

 rent types of growth forms in V. tricolor and V. arvensis, viz. the lines 

 2 and 4, both belonging to V. (irocnsis. The Fi-generation was inter- 

 mediate. The main axis was more than half upright, and the 

 branches about intermediate between the parents. The appearance of 

 Fl is to be seen in figure 3 E. 



F., showed a continuous variation. All kinds of transitions between 

 the erect branches of line 2 and the prostrate ones of line 4 were 

 found. Further, the position of the main axis and the branches varied 

 at least relatively independently of each other. Thus, types with an 

 erect main axis and prostrate branches were found. Types with 

 prostrate main axis and erect branches, however, were not noticed. 

 It is therefore possible that coupling was present în some degree. 



The measuring of the angles are rather difficult and therefore 

 no values were obtained. Of course, it is possible that some 

 plants have been put in a wrong class; especially may this be the 

 case with regard to the branches, which were rather difficult to 

 classify. The existence of several much ramified branches made the 

 estimation of the mean of the angle still more difficult. 



As is to be seen in table 18 the F.-generation is only complete 



