. Elementary botany : theoretical and practical. A text-book designed primarily for students of science classes connected with the science and art department of the committee of council on education . Botany. 24 Elementary Botany When cell division is about to take place, two nuclei are formed either by the division of the original one, or by its disappearance, and the formation of two fresh ones. The whole mass of the protoplasm now aggregates around these nuclei, and a cell wall is formed between the masses thus produced, growing inwards from the circumference to the centre, thus dividing th
. Elementary botany : theoretical and practical. A text-book designed primarily for students of science classes connected with the science and art department of the committee of council on education . Botany. 24 Elementary Botany When cell division is about to take place, two nuclei are formed either by the division of the original one, or by its disappearance, and the formation of two fresh ones. The whole mass of the protoplasm now aggregates around these nuclei, and a cell wall is formed between the masses thus produced, growing inwards from the circumference to the centre, thus dividing the mother cell into two daughter cells, each of which may grow to the size of the mother cell, and itself undergo division. The formation of reproductive cells we shall have to notice later on (page 117). Except in a few cases, cells do not remain through life individually separate, but ai-e united together to form ' tissues.' These may be grouped accord- ing to either their function, or their structure. Under the for- mer method of division we have two kinds, viz. meristem, which is a tissue where the cells remain vitally active and capable of di- vision, and permanent tissue, where the cells are no longer able to divide. If we arrange them according to their struc- ture, we distinguish those tissues which consist of elongated cells overlapping one another, and which are known as prosenchy- ma, and those which are formed of shorter cells placed end to end, or parenchyma. These 'â '.â ; 41âCells of stem of ;7c/«/^aja. two forms of tissucs, however, Mtristem cells in process of division ; A-, . nucleus ; dividing, a; fully divided, i. paSS the One into the Other bv (.After Prantl.) * â , . â ' endless gradations. Sometimes the term sclerenchyma is used to denote either prosenchymatous or parenchymatous tissues, where the walls of the cells have become very thick and hard, and often dark Please note that these images are extracted from scanned page images that m
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