. Introduction to structural and systematic botany, and vegetable physiology. Botany. 332 REPRODUCTION IN togamous plants. A few examples may be adduced, illustrative of the principal modes, beginning with the simplest plants. 654. Reproduction in Plants of a Single Cell (lOO). All such simple one-celled plants as Protococcus and the like (Fig. 79-83, 18 - 22), Desmidiacea3 and Diatomacese, are freely propagated by cell-multi- plication (33 - 36), — the division of their protoplasm or whole living mass into bodies which directly become new cells like the parent,— or by original cell-formation
. Introduction to structural and systematic botany, and vegetable physiology. Botany. 332 REPRODUCTION IN togamous plants. A few examples may be adduced, illustrative of the principal modes, beginning with the simplest plants. 654. Reproduction in Plants of a Single Cell (lOO). All such simple one-celled plants as Protococcus and the like (Fig. 79-83, 18 - 22), Desmidiacea3 and Diatomacese, are freely propagated by cell-multi- plication (33 - 36), — the division of their protoplasm or whole living mass into bodies which directly become new cells like the parent,— or by original cell-formation in their interior (29). This is non- sexual reproduction, and essentially answers to the well-known prop- agation of PhfEnogamous plants by buds, bulbs, offsets, &c. It is probable that this may not go on indefinitely in any plant. At any rate, not only do all the higher plants propagate in a different way, viz. by flowers, producing seeds, but probably all plants of the lower grade also have a sexual reproduction in some form or other. It is certainly the case in many one-celled plants, and in others almost equally simple in structure. As in Phasnogamous plants, sexual reproduction essentially depends upon the mingling of the materials of two distinct cells (as the pollen-cell and the embryonal vesicle, 579) ; and these cells in the lowest forms of vegetation represent individual plants. The simplest mode of such reproduction in the lowest plants, and that longest known, is what has been termed 655. Conjugation, This ia the mode in which two vast tribes of microscopic one-celled aquatic plants, the DesmidiaceiE and Diato- macece, are reproduced. They midti- ply rapidly, and apparently without limit, by successive division into two equal parts, which separate, each be- coming like the original. But at length two of these individuals, being en- dowed with the power of movement, come into contact; the firm or often silicious cell-wall ruptures or gives way in a definite m
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