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Page:Popular Science Monthly Volume 21.djvu/309

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The unicellular hairs found on young leaves of Verbena urticifolia, a common way-side weed, exhibit something like a nucleus at the base of the hair, from which center streams of protoplasm are constantly departing, to which they constantly return (Fig. 13). Fig. 14 shows the terminal cell of a hair taken from the petal of the purple lady's-slipper.

PSM V21 D309 Unicellar hairs of plants.jpg
Fig. 13.—Unicellular Hair of Verbena. Fig. 14.—Hair from Petal of Lady's Slipper.

Here the nucleus seems almost to be in the way. It is so large as nearly to close the narrow cell across from side to side, and the current appears crowded between the nucleus and cell-wall.

In the hairs that cover the common tomato-plant we may find beautiful transparent cells. In these cells sometimes the nucleus shows a vacuole, and the streams are always fine and large, but changeful as the shadows of passing clouds (Fig. 15).

But we must resort to plants belonging to the botanical order Cucurbitaceæ to find hair-cells showing greatest activity. In the hairs covering the forming bud of a common pumpkin-vine the cells are of