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Page:Popular Science Monthly Volume 18.djvu/638

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THE POPULAR SCIENCE MONTHLY.

nothing else, yet, as regards other essential structural characters, they deserve a much higher rank. Taking a section of the stem of Sigillaria, for example, and studying the arrangement of the tissues—the pith, wood, bark, and vascular bundles—we find a plan of structure that characterizes only the very highest of modern plants (Fig. 9). Apply the microscope to thin slices, and the most intimate connection with the pines is suggested; indeed, if there were only time, it might be shown that the range of relationship of these old plants extends over a wide section of the vegetable kingdom, and is of such a nature as to set them very much above their dwarfed representatives of the present woods, the club-mosses. In addition to Lepidodendrons and Sigillarias, the forests of the coal age supported many a tall pine, particularly on the uplands, while groves of reed-like calamites (Fig. 10) fringed the swamps; and the whole surface, both of swamp and upland grove, was covered with a dense undergrowth of magnificent ferns (Figs. 11, 12, 13). But the pines were not the pines of our woods, for some of them, through their broad, frond-like leaves and other characters, were allied to ferns, while all of them showed morePSM V18 D638 Coal fern hymenophyllitis alatus.jpgFig. 13.—Coal-Fern: Hymenophyllitis alatis. or less decided taints of characters inherited from club-mosses, or rather the characters were inherited with club-mosses from a common ancestor. The calamites, too, were a curiously mixed-up group, and even the ferns showed a most reprehensible lack of allegiance to the fern type, since most of them united characters that do not belong to ferns at all, but are found now only separated in the palms on the one hand, and the highest flowering plants on the other. It is extremely difficult to present in few words any clear picture of the old Carboniferous forests. The stately club-mosses towering above all competitors—real monarchs of the wood—ornamented from root to crown with beautiful carvings in regular and delicate designs; the magnificent ferns whose exquisite outlines are still preserved in the roof shales of every coal-seam; the dense, dark jungles, tangled and impenetrable; the heavy, steaming, miasmatic atmosphere; the astonishing luxuriance of all the vegetation—these all are themes that claim the attention of every writer or speaker on this subject. But to my mind the prime interest centers in the composite nature of the vegetation, with all its wonderfully puzzling and intricate relationships. He must be dull, indeed, who can not see that in this significant mingling and blending of characters, the old coal forests epitomize and foreshadow all subsequent vegetation. All the structural elements were there; almost every fundamental type had a place in some of the curiously constructed plans of plant-life, and all progress in higher vegetable