ZOOLOGY 



Color 



patterns in 

 sunflowers 



, o6>, and oo. The total result may be expressed by 

 a diagram, as follows, in which each zygote is repre- 

 sented within a square. Each combination of red and 

 orange is repeated four times, combining with the other 

 four. The red series is repeated vertically, the orange 

 transversely. 



It will be seen that, of the sixteen squares, nine have 

 at least one R and one 0, and therefore will be red on 

 orange, or chestnut red. Three have 0, but no R, and 

 are plain orange, like the wild ancestor. One has 

 neither R nor 0, and so is primrose. Finally, three 

 have R but no 0, and are red on a primrose background. 

 It is these last we aimed to get, and as was expected, 

 they present quite a new shade of color. The red is 

 wine-red or "old rose." Thus a new color variety is 

 "created," by recombining old factors. In the original 

 experiment giving this result the plants obtained were 

 71 chestnut-red, 19 orange, 25 wine-red, and 8 primrose. 

 The theoretical expectation, following the 9, 3, 3, I 

 ratio, was 69 chestnut, 23 orange, 23 wine-red, and 8 

 primrose. 



10. So far, we have considered only the shade of 

 color. It was surprising to find that, given a certain 

 color, it might appear in various different patterns. 



