aetter, as follows; the red is the acid salt, the blue is a neutral
metallic salt, and the violet is the anhydride of the anthocyanidin in
question, thus

Cl Cl
| |
O _____ O _____
HO__ / \ / \ __/ \ KO__ / \ / \ __/ \
| | | \_____/ | | | \_____/
| | | | | |
\ / \ / \ / \ /
C O C
| \
Red | \ Blue
| O _____
|/ \ / \ __/ \
| | | \_____/
| | |
\ / \ /
C

Violet

All of the natural anthocyanin pigments appear to contain a chlorine atom
attached directly to the ring oxygen, as shown in the above partial
formulas. In addition, they have four, five, or six hydroxyl (OH), or
methoxy (OCH_{3}), groups attached at various points around the three
rings. The following formula for _[oe]nidin_, one of the most complex of
these anthocyanidins, will illustrate their structural arrangement.

Cl
| _____OCH_{3}
O / \
HO__ / \ / \ _____/ \OH
| | | \ /
| | | \_____/
\ / \ / OCH_{3} OH
OH C

_Delphinidin_ is the corresponding compound without the two CH_{3} groups;
while _cyanidin_ contains only five OH groups; and _pelargonidin_, only
four OH groups.

The anthocyanin pigments are soluble in water, alcohol, and ether, the
solutions being red or blue in color according to the acidity or alkalinity
of the medium. Their presence in many species of plants is hereditable, as
these plants come true to color from seed, as in the case of red beets, red
cabbage, several species of blue berries, etc. In other cases, the
anthocyanin development depends largely upon the conditions of growth,
particularly those which prevail during the later stages of deve