The American botanist and florist; including lessons in the structure, life, and growth of plants; together with a simple analytical flora, descriptive of the native and cultivated plants growing in the Atlantic division of the American union . ides itself into two or more new cells. If FEETILIZATION. 143 these neAV cells cohere into a tissue assuming a definite form, asin the higher plants, the process is called ^rot()^^Ay but if theyseparate, each one still abiding separate, it is reproduction. 449. The embryonic vesicle is the expressive name of theembryonic cell of the FloweringPlants. It
The American botanist and florist; including lessons in the structure, life, and growth of plants; together with a simple analytical flora, descriptive of the native and cultivated plants growing in the Atlantic division of the American union . ides itself into two or more new cells. If FEETILIZATION. 143 these neAV cells cohere into a tissue assuming a definite form, asin the higher plants, the process is called ^rot()^^Ay but if theyseparate, each one still abiding separate, it is reproduction. 449. The embryonic vesicle is the expressive name of theembryonic cell of the FloweringPlants. It has its birth in thatlaro;e cell of the nucleus of theovule (§ 142) called the embryosac, and is in some way developedfrom the cytoblast (§ 380). Inappearance it may be like othernew cells; but in the impulse orinstinct with which it is endowed,it is immeasurably different. Itlooks not to the mere continuationof an old series, but is the projectorand pioneer of a new. But beforeit can enter upon its course of de-velopment so different from thedestination of common cells, itmust somehow be quickened andenergized with an impulse in thisnew direction. In other words,it must be fertilized—a processdependent on the pollen-grains(§ 121).. 521, Section of the ovary of Polygonum Pennsylvanicum, in process of fertilisation. (Mag-nified 20 diameters.) r, Natural size; «, one ofthe stamens, having discharged its pollen; t, agrain of pollen and its tube; s, styles and stig-mas; o, ovary, ovule, embryo sac containing theembryonic globule. The extremity of a pollen-tube is seen in contact with the embryo sac. 450. The annexed cut indicates all that is cer-tainly known of this recondite process. Thepollen-grain falls upon the stigma, imbibes thesaccharine moif>ture there, and its inner coatof protoplasm expands and protrudes throughthe aperture (one or more) of the outer crusta-ceous coat, in tlie form of an attenuated , like a radicle, sinks into the soft tissuesof the stig
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1870
