38o 



THE POPULAR SCIENCE MONTHLY 



I have drawn the " pure " red very dark, on the supposition that it will 

 be visibly more highly colored than anything yet seen, although this may 

 not prove to be the case. If it is distinguishable, we shall then perma- 

 nently isolate the red without further trouble ; if it is no different from 

 the impure reds, it will only be possible to separate the pure strain by 

 noting the results of numerous crosses made at random. 



yr 



RY 



l^/l. 



iCjii. 



DiAGEAM SHOWING THE FlEST CROSS MADE WITH THE RED SUNFLOWER, the TCSUlt 



obtained in 1911 and the expected result for 1912. y = yellow-ray factor; 



R = red-ray factor. 



Last year we made various new crosses, especially with the great 

 double " chrysanthemum-flowered " variety obtained from Dreer of 

 Philadelphia. If we can get this red, as we doubtless can, it will be a 

 striking plant, though perhaps less attractive than the single kinds. In 

 tabulating the characters crossed, I enumerated not only the ray color, 

 but also the color of the disc, the size of the heads, and the manner of 

 growth. In the coronatus X lenticularis cross, everything except ray 

 color is the same on both sides, so there is nothing to be noted. In the 

 coronatus X Russian cross, it is quite otherwise. We find that dark 

 disc is uniformly dominant over yellow ; the size of the heads in the cross 

 is greater that that of lenticularis^ but much less than that of the 

 Eussian ; and the manner of growth is intermediate, at first simple like 

 the Eussian, but eventually branching at the top. It is evident that 

 there is some correlation between the manner of growth and the size of 

 the heads, as a plant could not well support more than one big head of 

 the Eussian type. A certain incompatibility between the two varieties 

 seems to be indicated by a number of monstrous (fasciated) plants. 



The accompanying diagram shows the Eussian coronatus cross in 

 relation to growth form, and in the third line the expected outcome in 

 1912. 



