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ANALYTICAL CLASS-BOOK OF BOTANY. 



extended in ita whole length, nnd forms the stem. The 

 young plant is nourished by albumen, starch, and ether 

 nutritious substances contained in the seed, until it has 

 developed a root and leaves, when it becomes entirely 

 - lt'-.le|.endent. procures its own food, and elaborates the 

 substance of its own tissues. But as starch is insoluble 

 in cold water (57), and the vegetable tissues cannot take 

 np solid particles, this highly nutritive substance, being 

 acted on by certain azotized substances contained in the 

 seed (71), is decomposed, and converted first into dex- 

 trine, which, you will remember, is soluble in cold water, 

 and then into sugar. In most dicotyledonous plants, 

 the cotyledons rise out of the ground, and, expanding 

 into a pair of thickened leaves, as in the Garden Bean, 

 fig. 16, contribute to the nourishment of the young plant, 

 not only by their fleshy substance, but by developing 

 chlorophylle (65). The germination of a monocotyledonous 

 plant is well shown in the Oat, fig. 19, and the Maize, fig. 

 17; and that of a Dicotyledonous plant at fig. 16. 



507. The periods that elapse between the times of 

 planting and germination in seeds, range from a few days 

 to two years. Cabbage will germinate in two days, 

 the Turnip in three, Grasses in a week, Hyssop in a 

 mouth, some Pines in a year, and the Holly in two 

 years. 



508. Since the facts of this chapter embrace many 

 principles which are dry and difficult in their very na- 

 ture, they may be made more familiar by reviewing them 

 collectively. The SEED consists of a Nucleus and its 

 Integuments. The external Integument is the Episperm, 

 the interior one the Endosperm, the latter not always 

 being present. The parts of the Nucleus are the Albu- 

 men and Embryo, the albumen not always present. The 

 opening in the integuments of the ovule is the Foramen ; 

 the part to which it is attached is the placenta ; the stalk 

 which unites it to the placenta is the Funiculus; the 

 base of the ovary which is joined to the funiculus, and in 

 separating leaves a scar, is the II Hum; and the point 

 from which are sent off nutritive vessels between the 

 nucleus and its integuments is the Chalaza. The nu- 

 cleus receives the influence of the pollen through the 

 foramen, ami its nourishment from the placenta, through 

 the funiculns. In fig. 10, which represents a vertical 



i of the Garden Pea, g is the embryo, t its common 

 axis, r the radicle, m is the foramen, te the episperm, c 

 the endosperm, c the fleshy cotyledon, ch the chalaza, 



Is Uw Primary Aits Root or Stem (ll.'O t By wuat Is tbe young pUat 

 MVfcbwl bow long? Why will not Uw vegetable times tako np starch? 

 Uder wbat form will they do w t In wbtt pluti do Uw Cot rltdont rlw oat 

 of ground whit form bow useful T How toon will the C*bbtge plwt get- 

 rolnfiu- Turnip Grsases Plow Holly? Remplintatr. Whl rlrriini- 



7V7/> the nutritive vessels, and pi the placenta. The 

 cells containing albumen and starch arc Keen in the seed 

 of Rye, fig. 15. At fig. 9 is seen the whole fruit of the 

 Pea. Its parts have lately been explained. Recall 

 them. 



DISSEMINATION OF SEEDS. 



509. Many circumstances assist in this great work. 

 The plumose appendages of the Compositae, of which the 

 Thistle-down is a familiar instance, waft the seeds through 

 the air, often to a great distance. A seed of the Robin's 

 Plantain, one of this Order, was carried across the At- 

 lantic in a stuffed bird, about the middle of the seven- 

 teenth century, and now it has overspread all Europe. 

 A similar instance of exotic dissemination is furnished 

 by the Cardoon Thistle, which is native of Southern 

 Europe'and Northern Africa. The seeds of this plant 

 having been conveyed by some means to La Plata, its 

 progeny have overspread the great Pampas of the Cordil- 

 leras, for nearly two hundred miles in every direction. 

 They cover whole tracts so closely with their stout stems 

 and spinesceut leaves, that no animal can get through the 

 impenetrable barrier, which is sufficient to repel an in- 

 vading army. The seeds of many others of the Compos- 

 ita) are furnished with hooks and spines, which adhere to 

 the fur of animals, and to other bodies ; while those of 

 the Ash, Beech, and Maple, spread their wings, and fly 

 abroad on the same great errand. River and ocean cur- 

 rents also assist in the dispersion of seeds. Those of the 

 Cocoa-nut and Mahogany arc transported from tropical 

 America to the North Cape, and many others make 

 similar voyages. Some flowers, as the Balsamine, fig. 9, 

 have elastic pericarps, which in bursting scatter the seeds 

 at a considerable distance. Seeds are also carried in tin- 

 stomachs of birds, or they are stored up by animals for 

 their winter food, and thus planted at a distance from 

 the parent soil ; and in this way forest trees are often 

 propagated. Even little children, as with their light 

 hreath they blow away the downy seeds of the Thistle 

 and Dandelion, or slyly fasten the hooked Burdock fruits 

 in each other's clothes and hair, are unconsciously assist- 

 ing in this great work of the Greater. 



LONGEVITY OF SKI 



510. Some seeds lose their vitality almost as soon as 

 11 from the plant, but many are very tenacious of 



life. The seeds of Grasses often preserve their vitality 

 for ii long period. Maize nnd Rye will germinate after 



stancet assist In dlsKmlnaUon of seeds? How In the Composite tbe IlalMiu- 

 Ine Wlnpid foods' What oflcct bavo river and ocean currents birds 

 quadrupeds sport* of children ? Fact "f lloMn'n 1'lalntaln- . 

 ThWIoJ CnmparmllTP lonsovlly >f ni-eds? 1lowln<?i IKvi. 



