296 Journal oj Agricultural Research voi. iv, no. 4 



occur in cells free from plastids or in the vacuoles of cells containing 

 plastids, but not associated with them as a part of the organized body 

 or plastid. These pigments have one property in common with the chro- 

 mophyll substances — i. e., with alkalies, potassium cyanid, and sodium 

 phosphate they assume some shade of green. They are distinguished, 

 however, by the fact that the colors are markedly affected by acids and 

 alkalies and by iron salts. The fact that these substances are so sensitive 

 to reagents probably accounts for the various shades and tints charac- 

 teristic not only of flowers but of leaves as well. Kraemer has observ^ed 

 in the germinating kernels of black Mexican sweet corn that even in 

 contiguous cells the constituents associated with the dye vary to such 

 an extent that the pigment in one cell is colored reddish, in another 

 bluish green, and in another purplish. 



COLOR HEREDITY 



It will be seen that the nature of color is very complex, and conse- 

 quently its heredity is equally so. Mendel's studies of peas and many 

 other similar plants seem now comparatively simple, because they deal 

 with characters which are easily distinguishable wath little reaction of 

 one upon the other. Each unit was found to be separately heritable 

 and could quite easily be traced from generation to generation. Not 

 so with colors, the units of which are obscure; being chemical in nature, 

 reactions of various sorts occur, making experimentation difficult. 



RESULTS OF CROSSING 

 SERIES I 



Pollen parent. — A pale rosy-pink variety known commercially as 

 Camea. The color corresponds to shade i on page 129 of the Repertoire 

 de Couleurs, designated hereafter as "shade 129-1." This variety has 

 a white eye — that is, the center of the flower is white and arranged as a 

 distinct pattern (PI. C). 



Seed parent. — A violet-purple variety (192-3) known in commerce 

 as Eclipse. This variety had a dark eye — that is, the center of the 

 flower had a denser, deeper color than the remainder of the flower, but 

 without any particular pattern. 



First and second generation hybrids. — ^The F^ hybrids were unlike 

 either parent. They were Tyrian rose (155-4), with a dark eye. The 

 color of the F^ hybrids immediately suggested the presence in the parents 

 of complementary color factors, which were united to produce something 

 different from either parent. 



All plants having similar colors were placed together in groups and the 

 numbers recorded. Table I gives the results of the Fj hybrids grouped 

 as accurately as possible in this way. 



