Wakeman—Pigments of Flowering Plants. 837 
While the flavone pigments are found in all parts of the plant 
they occur most frequently in the roots, wood, bark and leaves. 
When they appear to be the pigment to which the flower owes 
its color, the blossoms are either pale yellow or almost white. 
In some instances, as the occurrence of kaempherol in the blue 
flowers of Delphinium consolida and Delphinium zali it is plainly 
evident that the color is not due to the presence of the flavone 
derivative but to some other pigment or pigments. 
Willstaetter in his work upon anthocyanin has shown that in 
the Delphiniums the color is due to delphinidin, probably a po¬ 
tassium salt of delphinidin. Delphinidin, according to Will¬ 
staetter, is isomeric with quercetin and morin, both of which 
are hydroxy substitution products of kaempherol. 
The flavone derivatives are not quinoid in character. All 
can be, however, theoretically, and some have been, actually, 
oxidized to quinoidal compounds (See Chrysin 2 . and quercetin 3 .). 
These quinones are deep red in color and closely resemble, in 
their behavior toward reagents, the red and blue pigments of 
flowers (anthocyanins). These quinones can be reduced to the 
corresponding hydroquinones which form either colorless or pale 
yellow crystals. 
From a consideration of the above reactions, also as a result 
of observations upon the distribution of anthocyanin, and from 
experimental evidence on the concentration of sugars and glu- 
cosides in various tissues, on the existence of enzymes, and on 
sugar feeding, there has recently been formulated a hypotheses 
(Miss Muriel Wheldale 4 ) that: The soluble pigments in flower¬ 
ing plants, termed anthocyanin, are oxidation products of 
colorless chromogens, existing in the tissues as .glucosides. The 
production of the glucoside from the ehomogen and sugar is in 
the nature of a reversible enzyme reaction: chromogen + Sugar 
= glucoside + water, and the oxidation of the chromogen, which 
is effected by one or more enzymes, can take place only after its 
liberation from the glucoside. 
According to Miss Wheldale this hypothesis brings the forma¬ 
tion of anthocyanine into line with that of pigments formed 
after the death of the plant (indigotin etc.) It is not opposed 
to the quinhydrone hypothesis of pigmentation and it is in ac- 
2 Ber., 45, 499. 
3 Ber., 44, 3,487. 
4 Jr. Genetics, 1, 133, (Jr. Chem. Soc., A. II, 80). 
