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Page:Popular Science Monthly Volume 21.djvu/307

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PLANT-CELLS AND THEIR CONTENTS.

into forms organic, and the earth filled with the children of life, the very essence of the living cell—the protoplasm. To this protoplasm we now turn our investigation.

Twelve or thirteen years ago this word—the name, to say nothing of the thing named—would have come all but unknown to the general reader. But to-day, thanks to the continuous discussions of the last decade, the word needs no introduction. All our readers know that

PSM V21 D307 Cross section of petiole with crystals in the cells.jpg
Fig. 8.—Cross-Section of Petiole of Begonia-Leap, shows Crystals in the Cells (copied from Prantl.)

protoplasm is the simplest form of living matter with which we are acquainted, is the living element of every living cell. One of the most characteristic phenomena of life is independent motion, and protoplasm more frequently reveals itself by moving. Such is the case in the cells we are now considering. In 1869 Professor Huxley set the thinking world all agog by describing, in a passage of wonderful accuracy and beauty, what he could see of moving protoplasm in the hair of a stinging nettle. Nettle-hairs and vegetable hairs generally consist either of a single elongated cell, or of a series of oblong cells arranged in a filament. Moreover, such hairs, or trichomes, are usually colorless, transparent throughout, and afford, therefore, cells admirably adapted to microscopic examination. Hairy plants are very common, so we may corroborate Professor Huxley's statements by observations made almost anywhere. Let us examine a hair taken from the evening-primrose. Here, under a magnifying power of from 400 to 500 diameters, we may see within the hair a delicate current sweeping down one side to the point, turning abruptly with slight delay, and then returning by the opposite side of the cell, leaving in the center a neutral space filled with cell-sap, across which the oppositely moving streams seem never to pass, in which they are never lost. No nucleus is present, nor any central station of power. The tiny streamlet pours on, self-guided