50 SECTIONAL ADDRESSES 
The greater number of the anthocyanins fall into a comparatively 
restricted number of categories, including : 
(a) the 3-monoglucosides and 3-monogalactosides, 
(6) the 3-rhamnoglucosides and other 3-pentoseglycosides, 
(c) the 3-biosides, 
(d) the 3 : 5-diglucosides, and 
(e) the acylated anthocyanins. 
It is unnecessary to recount the steps taken in reaching these conclusions, 
but they have been finally justified by synthesis in many instances. 
In group (a) we find callistephin (XVIII), the monoglucoside of pelar- 
gonidin occurring as one of the pigments of the aster and as the main 
pigment of scarlet carnations and many other flowers; the related 
galactoside, fragarin, is the colouring matter of the strawberry. 
In the cyanidin series the corresponding pair is chrysanthemin and 
idwin (XIX), the former of wide distribution and the latter occurring 
in the skins of cranberries and in the leaves of the copper beech. 
Peonidin 3-monoglucoside (XX), termed oxycoccicyanin, is found in 
the skins of the larger American cranberries and cenin or malvidin 
3-monoglucoside (XXI) is the colouring matter of the skins of purple- 
black grapes, as well as of certain cyclamen and primule. The delphi- 
nidin representative undoubtedly occurs in bilberries in admixture with 
other pigments, and it has not yet been fully examined ; the petunidin 
and hirsutidin representatives have not been isolated from natural sources, 
although there is reason to believe that the former occurs in the berries 
of the Darwin barberry and the latter has been synthesised. 
Cl Cl OH 
HO 6 | pon coer e 
O0-C,H,05 CA /0-CeliniOs 
HO 
(XVIII) (XIX) 
ee OMe — OMe 
HOY On. < Son HO on < You 
as 
OMe 
WZ O-C,H,,0; /O-C.H1105 
HO HO 
(XX) (XXI) 
In groups (b) and (c) we find large classes of anthocyanins of which 
only a few representatives have been closely studied. These include 
keracyanin (cyanidin 3-rhamnoglucoside), probably identical with antir- 
rhinin (isolated by Miss R. Scott-Moncrieff), and mecocyanin (XXII), 
