Wakeman—Pigments of Flowering Plants. 
831 
Dobbie and Lander,—Proc. Chem. Soc., 17, p. 255. 
Fleitmann,—Ann., 59, p. 160. 
Freund,—Ann., 397, p. 1. 
Freund and Beck,—B., 37, p. 4673. 
Freund and Meyer,—B., 40, p. 2604. 
Gadamer,—Chem. Ztg., 26, p. 291, 385; Arch. Pharm., 239, p. 
648; 243, p. 12, 31, 43, 89, 246. 
Gaze,-—Beilstein, Handb. organ. Chem., 3, p. 800. 
Gordin,—Arch. Pharm., 39, p. 638; 240, p. 146. 
Hlasiwetz and Gilm,—Ann., 115, p. 45 ; 122, p. 256; Suppl. 
II. p. 133. 
Henry,—Ann., 115, p. 133. 
Link,—Arch. Pharm., 230, p. 734. 
Mosse and Tauz,—Chem. Centralbl., 1901, II. p. 786. 
Perkin, A. G.,—Jr. Chem. Soc., 67, p. 413; 71, p. 1189. 
Perkin, H. W.,—Jr. Chem. Soc., 55, p. 78; 57, p. 1037. 
Perkin, W. H. and Robinson,—Jr. Chem. Soc., 97, p. 305. 
Perrins,—Ann., Suppl. II. p. 176. 
Schlotterbeck,—Jr. Am. Chem. Soc., 24, p. 238. 
Schmidt,—Handb. Organ. Chem., 3, Aufl. 3, p. 798. 
Troege and Linde,—Arch. Pharm., 238, p. 6. 
Weidel,—B., 12, p. 410. 
I. B. Pigments referable to diphenyl — 1 , 3—propene series of 
hydrocarbons. 
Just as the larger number of natural coloring matters of the 
degree of saturation C n H 2n _ 14 , may be referred to diphenyl 
methane, so by far the greater number of those of this degree 
of saturation, the flavone derivatives, may be referred to a sim¬ 
ilar hydrocarbon, diphenyl propene. Indeed the relationship 
of the flavone group to the xanthone group is much closer than 
would be inferred by simply referring the individual compounds 
to their underlying hydrocarbons. By comparing the struc¬ 
tural formula of xanthone with that of flavone it will be seen 
that both compounds contain the y-pyrone group: more than 
this, they contain the benzo y-pyrone group, designated by 
Bloch and Kostanecki 1 . the chromone group. In the xanthone 
derivatives the chromone group is condensed with another ben¬ 
zene nucleus forming dibenzo y-pyrone, while in the flavone 
derivatives it is united with a phenyl group forming phenyl- 
benzo-y-pyrone. With this similarity in' structure it is by 
1 B., 33, 471. 
