. A class-book of botany, designed for colleges, academies, and other seminaries. Illustrated by a flora of northern, middle, and western states; particularly of the United States north of the Capitol, lat. 38 3/4. Botany; Plants; Plants. 36 THE FLOWER. usually spherical, but in some plants cubical, in others triangu- lar, in others still, polygonal, &c, always being of the same form in the same species. (Fig. 7.) a. Each grain of pollen has been ascertained to consist of a membranous sack containing a fluid. In tliis fluid are suspended molecules of inconceivable minuteness, possessed of
. A class-book of botany, designed for colleges, academies, and other seminaries. Illustrated by a flora of northern, middle, and western states; particularly of the United States north of the Capitol, lat. 38 3/4. Botany; Plants; Plants. 36 THE FLOWER. usually spherical, but in some plants cubical, in others triangu- lar, in others still, polygonal, &c, always being of the same form in the same species. (Fig. 7.) a. Each grain of pollen has been ascertained to consist of a membranous sack containing a fluid. In tliis fluid are suspended molecules of inconceivable minuteness, possessed of a tremulous motion. When the membrane is exposed to moisture, it swells and bursts, discharging its contents. (Fig. 12.) 71. Physiological structure. The filament consists of a bundle of delicate ligneous tissue, with spiral vessels, surrounded by cellular tissue, the same tissues which compose the stem of the leaf (260). The same tissues have also been traced into the connectile. The anther consists almost wholly of cellular tissue, corresponding to the fleshy substance (parenchyma) of the leaf. The pollen consists of disintegrated bladders of the same tissue. 72. Theoretical structure. Thus it is evident, as we have already seen, that however much the stamen may differ in aspect from a leaf, they both have the same original plan. This is further evident, from the gradual transition of sta- mens into petals, as seen in the water-lily or the double rose. In the former, the process is so gradual that the outer whorls exactly resemble petals, except in having the tops developed into yellow anthers, while in the rose we find organs in every conceivable state of transition from stamens to petals. That the petals are modi- fied leaves, will hereafter be more definitely shown (106).. FIG. 8. —Stamens of the water-lily gradually passing into petals. 73. The stamens vary in the different kinds of plants, in re- spect to their number, position, relative length, connection, and presenc
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