Text-book of structural and physiological botany . Fig. 49.—Groups of crystals; « from theleaf of Begonia heracleifolia (quad-rate octohedra) ; b from the stem ofUrostigma elasticti7n. (x 660.) Fig. 50.—Cell from the stem of Aloeretusa, with raphides. (x 320.) called pseudo-compound where several are enclosed together in onevesicle, as in a grain of chlorophyll (Fig. 47). Only in a comparatively The Cell as an Individual. 29 small number of groups of plants has no starch been fcund up to thepresent time, as in many Algae and Fungi. The purpose of the forma-tion of starch is that it may be stor
Text-book of structural and physiological botany . Fig. 49.—Groups of crystals; « from theleaf of Begonia heracleifolia (quad-rate octohedra) ; b from the stem ofUrostigma elasticti7n. (x 660.) Fig. 50.—Cell from the stem of Aloeretusa, with raphides. (x 320.) called pseudo-compound where several are enclosed together in onevesicle, as in a grain of chlorophyll (Fig. 47). Only in a comparatively The Cell as an Individual. 29 small number of groups of plants has no starch been fcund up to thepresent time, as in many Algae and Fungi. The purpose of the forma-tion of starch is that it may be stored up in the cells as a reserve food-material, which becomes dissolved in the subsequent formation of new. Fig. 51.—Longitudinal section through the inner bark of the stem of Hoyacarnosa. Together with the thin-walled parenchyma, partly containingchlorophyll with starch-grains, partly crystals d and k r, are bands ofvery strongly thickened pitted parenchymatous cells p, and laticiferousvessels in m. (x 250.) cells, and can then be used as a formative material. It is, therefore, de-posited in especially large quantities in bulbs, tubers, seeds, pollen-grams, and generally in those organs which, when vegetation awakes, 30 Strtictural and Physiological Botany. form the starting-points of the new formation of large numbers of cells.(See also Chap. V.) Crystals occur in particular cells in almost all the higher vascularplants, less often also in the less highly organised Cryptogams ; and inConifers are also frequently found imbedded in the cell-wall. Theyconsist of calcium oxalate. The crystals, when separate, contain six equi-valents of water of crystallisation ; their stem-form is a blunt q
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