Page:Popular Science Monthly Volume 3.djvu/485

Rh called spores, or sporules, generally invisible to the naked eye, and differing from true seeds in germinating from any part of their surface instead of from two invariable points. Besides this grand distinguishing mark, they possess several other peculiar qualities in common. They consist of cells only, and hence are often called cellular plants, in contradistinction to those plants which are possessed of fibres and woody tissue. Their development is also superficial, growth taking place from the various terminal points; and hence they are called acrogens and thallogens, to distinguish them from monocotyledonous and dicotyledonous plants. Popularly, they are known as mosses, lichens, algae, and fungi. They open up a vast field of physiological research. They constitute a microcosm, a strange minute world underlying this great world of sense and sight, which, though unseen and unheeded by man, is yet ever in full and active operation around us. It is pleasant to turn aside for a while from the busy human world, with its ceaseless anxieties, sorrows, and labors, to avert our gaze from the splendors of forest and garden, from the visible display of green foliage and rainbow-colored blossoms around us, and contemplate the silent and wonderful economy of that other world of minute or invisible vegetation with which we are so mysteriously related, though we know it not. There is something exceedingly interesting in tracing Nature to her ultimate and simplest forms. The mind of man has a natural craving for the infinite. It delights to speculate either on the vast or the minute; and we are not surprised at the paradoxical remark of Linnæus, that Nature appeared to him greatest in her least productions.

These plants once occupied the foremost position in the economy of Nature. Like many decayed families whose founders were kings and mighty heroes, but whose descendants are beggars, they were once the aristocracy of the vegetable kingdom, though now reduced to the lowest ranks, and considered the canaille of vegetation. Geology reveals to us the extraordinary fact that one whole volume of the earth's stony book is filled almost exclusively with their history. Life may have been ushered upon our globe through oceans of the lowest types of Confervœ, long previous to the deposit of the oldest palaeozoic rocks as known to us; and for myriads of ages these extremely simple and minute plants may have represented the only idea of life on earth. But, passing from conjecture to the domain of established truth, we know of a certainty that, at least throughout the vast periods of the Carboniferous era, ferns, mosses, and still humbler plants, occupied the throne of the vegetable kingdom, and, by their countless numbers, their huge dimensions, and rank luxuriance, covered the whole earth with a closely-woven mantle of dark-green verdure—from Melville Island in the extreme north, to the islands of the Antarctic Ocean in the extreme south. The relics of these immense primeval forests, reduced to a carbonaceous or bituminous condition by the