GORE, H. C.--"Experiments on the Processing of Persimmons to Render them Nonastringent," U. S. Department of Agriculture, Bureau of Chemistry _Bulletin_ No. 141, 31 pages, 3 plates, 1911; and No. 155, 20 pages, 1912. LLOYD, F. E.--"The Tannin-Colloid Complexes in the Fruit of the Persimmon, _Diospyros_," in _Biochemical Bulletin_, Vol. 1, No. 1, pages 7 to 41, 34 figs., New York, 1911. CHAPTER VIII PIGMENTS Practically all plant structures contain pigments. These may be considered as of two types: (_a_) the vegetative pigments, which have a definite energy-absorbing rôle in the metabolic processes of the tissues which contain them, and (_b_) the ornamental pigments. It is probable that the same chemical compound may serve in either one of these capacities under different conditions, but, in general, it is possible to assign either a definite vegetative, or physiological, use, or else a simple ornamental, or biological, significance to each of the common pigments. The first type is found widely distributed through the protoplasm, or cell-sap, of the plant structures; while the ornamental pigments are located chiefly in the epidermal cells, especially of flowers. With respect to their colors, the plant pigments may be grouped as follows: Green--the chlorophylls. Yellow--the carotinoids, flavones, and xanthones. Red--phycoerythrin, lycopersicin, anthocyanin. Blue--anthocyan derivatives. Brown--phycophæin, fucoxanthin. Of these, the chlorophylls, the carotinoids, phycoerythrin (in red sea-weeds) and phycophæin (in brown sea-weeds) are generally vegetative pigments; while the others form the basis for most of the ornamental pigments, although they may have a definite energy-absorbing effect, in some cases. THE CHLOROPHYLLS