Wakeman—Pigments of Flowering Plants. 863 
pigments, is obtained, the qninoidal configuration as a possible 
explanation was abandoned and the arrangement of double 
bonds of the pyrylium grouping adopted instead. Whether 
or not the difficulties in the way of accepting Willstaetter’s 
furmula are more easily explained away than are those in the 
way of accepting the quinoidal formula is still a matter of 
opinion. 
Among the anthocyanins thus far studied pelargonidin is 
isomeric with apiginin and galangin. Cyanidin is isomeric 
with luteolin, lotoflavin, fisetin, and kaempherol. Paeonidin, 
a methyl ether of cyanidin is isomeric with kaempherid, a 
methyl ether of kaempherol. Delphinidin is isomeric with 
quercetin and morin, while myrtillidin, a methyl ether of del¬ 
phinidin is isomeric with rhamnetin and isorhamnetin, both 
methyl ethers of quercetin, and malvinidin and oenidin, 
dimethyl ethers of delphinidin are isomeric with rhamnazin, 
a dimethyl ether of quercetin. 
The isomerism of the above named compounds is probably 
not to be doubted. That this isomerism consists only in the 
different position of a hydroxyl group in the pyrylium ring, 
even in acid combination, is open to question, since no such 
marked difference in properties exists between the flavonols 
and the true flavones as is found to exist between the flavone 
derivatives and the anthocyanins. 
None of the neutral pigments, isomeric with the flavone pig¬ 
ments appear to have been isolated as such. They have been 
obtained as oxonium salts formed by the addition of a mole¬ 
cule of acid to a molecule of the pigment, as the colorless pseudo 
base, obtained by the elimination of the elements of hydro¬ 
chloric acid and the addition of the elements of a molecule of 
water, and as the color base, a colored modification of the pseudo 
base into which it changes upon standing in concentrated solu¬ 
tion. 
According to Willstaetter red and pink colors in the organs 
examined are due to acid compounds of the pigment, oxonium 
salts; purple and violet colors to the free pigments; and blue 
colors to metallic derivatives of the pigment. The blue corn¬ 
flower is probably colored by the potassium salt of the cyanin, 
and the scarlet geranium by the compound of pelargonin with 
tartaric acid, while the purple delphinum is supposed to be col¬ 
ored by the neutral delpninin. 
