I was standing on the tough, hollow rind of such a birch, so long, long dead that its carcass had gone to dust, leaving only this empty shell that looked like a broken, half-buried piece of aqueduct. It was neither tree nor pipe, however, but the House of Porcupines, as I could plainly hear by the grunting inside. A pile of droppings at the door of the house told the story of generations of porkies going in and out before the present family came into their inheritance. I knocked on the rubbery walls with my foot, but not hard, for I might break through and hurt Mother or Father Porky, or possibly the baby that I saw along the pond that night. No careful, right-minded person steps on or hurts a porcupine in any manner. I went on out of the sound of their teeth, for chattering teeth are not consoling, and the woods were gray enough. Gray and vast and magnificently ruinous, yet eternally new they were, the old walls slowly crumbling, and over them, out of their heaped disorder, the fresh walls rising to the high-arched roof that never falls. To-day the deep, hollow halls were shut to me by the arras of the gloom, and so smoky rolled the rain beneath the roof that even the black rafters of the birches were scarcely visible; but all the closer about me, in the wildest wealth and splendor, lay the furniture of the forest floor. Never were wools dyed and woven with a pile so rich and deep as the cover of mosses and lichens that carpeted this rude, cluttered floor. Rolled and wrinkled and heaped up over the stumps, it lay, nowhere stretched, nowhere swept, a bronze and green and gold ground, figured and flowered endlessly; and down the longest, deepest wrinkle a darkling little stream! It was a warp of sphagnum moss with woof of lichens, liverworts, ferns, mushrooms, club mosses, and shier flowers of the shadows, that was woven for the carpet--long, vivid runners of lycopodium, the fingered sort, or club moss, and its fan-leaved cousin, the ground pine, now in fruit, its clusters of spikes like tiny candelabra standing ready to be lighted all over the floor; and everywhere, on every tree-trunk, stump, and log, and stone the scale mosses, myriads of them, in blotches of exquisite shapes and colors, giving the gray-green tone to the walls as the sphagnums gave the vivid bronze-green to the floor. Down to about the level of my head, the dominant note in the color scheme of the walls, hung the gray reindeer moss, tufts and shreds and pointed bunches of it like old men’s grizzled beards. Some of the spruces and twisted cedars were covered with it. Shorter in staple than the usnea of the South, stiffer and lighter in color, it is far less somber and funereal; but a forest bearded with it looks older than time. This moss is the favorite winter food of the moose and caribou and deer, and so clean had the moose and deer eaten it from the trees, up as high as they could reach, that the effect on a clear day was as if a thin gray fog had settled in the