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sand, provided no change of circumstances either exposes it to decay or calls its vital properties into activity. Hence, where seeds have been buried deep in the earth, not by human agency, but by some geological change, it is impossible to say how long anteriorly to the creation of man they may have been produced and buried, as in the following curious instance: Some well-diggers in a town on the Penobscot River, in the State of Maine, about forty miles from the sea, came, at a depth of about twenty feet, upon a stratum of sand. This strongly excited their curiosity and interest, from the circumstance that no similar sand was to be found any where in the neighborhood, and that none like it was nearer than the sea-beach. As it was drawn up from the well it was placed in a pile by itself, an unwillingness having been felt to mix it with the stones and gravel which were also drawn up. But when the work was about to be finished, and the pile of stones and gravel. to be removed, it was necessary also to remove the sandheap. This, therefore, was scattered about the spot on which it had been formed, and was for some time scarcely remembered. In a year or two, however, it was perceived that a number of small trees had sprung from the ground over which the heap of sand had been strewn. These trees became, in their turn, objects of strong interest, and care was taken that no injury should come to them. At length it was ascertained that they were Beach-plum-trees; and they actually bore the Beach-plum, which had never been seen except immediately upon the sea-shore. The trees had therefore sprung from seeds which were in the stratum of sea-sand that had been pierced by the well-diggers." It can not be doubted, as Carpenter concludes, that the seeds of the Beach-plum had lain buried since the remote period when that part of the state was the shore of the slowly-receding sea.

Such a fact, so striking and so circumstantially recorded, is only of the same nature as others less critically noted, which daily pass before our eyes in the upspringing of vegetable forms from the diluvial materials thrown out of wells, cellars, and other excavations.

The bones, the hair, and even the flesh of the extinct mammoth have been preserved in glacial deposits on the shores of Siberia. In so complete a state of preservation has the flesh been found, that dogs and bears greedily devoured it. If a material so perishable as muscular fibre could be preserved since an epoch which antedates authentic history, is it not more probable that the oily tissues of vegetable seeds could resist the tendency to decay under similar circumstances?

It must be confessed that the crucial observation is yet to be made. If vegetable germs exist in the drift, they can be discovered beforehand. I am not aware that any thorough search has ever been made for them; but, until they have been actually detected, it is probable that even the convincing facts cited above will fail to secure universal assent to the doctrine of the prolonged vitality of the seeds of pre-glacial vegetation. While, however, the case is far from demonstrated, it may fairly be submitted that the explanation of certain facts afforded by this theory is less presumptuous and improbable than the supposition of spontaneous generation, the fortuitous distribution of seeds by any modern agency, or any other explanation. that has yet been offered.

CHAPTER XXIV.

PRAIRIES AND THEIR TREELESSNESS.

THE prairies of the Mississippi Valley, especially those lying within the limits of the great State of Illinois, constitute one of the most remarkable features of North American topography. Hundreds of thousands of acres, stretching through all the central and western portions of the state, present a scene of almost unbroken level and treelessness. The great prairies are neither a perfect plain, nor in all cases completely undiversified with arboreal vegetation. The surface is generally undulating; and here and there rise gravelly knolls and ridges on which the timber has obtained a foothold. But these wooded spots are often many miles apart, and scarcely serve to rest. the eye, wearied with the monotony of an interminable clearing, fenceless meadows, and unsheltered farm-houses.

The traveler, leaving Chicago by one of the great southern routes—for instance, the Chicago, Alton, and St. Louis Railway-passes out through the muddy and straggling outskirts of the Western metropolis, and, ere he has thought of the great prairies through which he had expected to pass, he finds himself at sea. Looking from his car-window, the country landscape seems at first to be entirely wanting. One feels as if passing over a trellis-bridge three hundred feet above the surrounding region. The customary objects -forests, shade-trees, fences, houses, distant hills-which elsewhere lift themselves to the horizontal plane of the eye, are not here. The traveler must make the second effort, and look down upon the level of the country upon whose

bosom he has launched. The sensation is that which one experiences in going to sea. The rattling train is easily transformed into the puffing and creaking steam-ship, while the interminable prairie, mingling its distant and softened green with the subdued azure of the summer sky, can be likened to nothing but the ocean's boundless expanse. The ever-recurring undulation of the prairie is the grand oceanswell which utters perpetually a reminiscence of the last storm, while the evening sun, with dimmed lustre, settles down into the prairie's green sod, as to the mariner he sinks into the emerald bosom of the sea.

Illinois has been styled the garden state of the West. The deep, rich, pulverulent soil of the upland prairie, and especially its readiness for the plow, without the intervention of a year's hard labor in opening a clearing, have always constituted powerful attractions for the settler from the stony soils of New England, and the wooded regions of the other states. It is extremely doubtful, however, whether the absence of forests over the area of half a state possesses a balance of advantages. Forests possess immense utilities in addition to furnishing lumber and fuel. This discovery was long since made in the denuded regions of the older European countries; and Americans are talking at times as if they were growing wiser. Even the cobblestones of a New England or New York soil are not unmitigated inconveniences. During the day they absorb the warmth of the sun, and at night they retain it and impart it to the soil. In times of drought they screen the soil from the direct rays of the sun, and thus moderate the intensity of the heat. They diminish the evaporating surface of the soil, and thus diminish the effects of continued droughts. A loose stone is a shade; but, unlike a tree, it has no roots of its own to creep about and steal the moisture from weaker forms of vegetation. A few stones do not

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diminish materially the amount of soil upon an acre; and, with the benefits which they confer, it is doubtful whether they are not actually to be desired, especially in regions subject to drought. A field will produce no more grain with the stones picked out than with the stones left in.

From our earliest knowledge of the prairies, speculation has been rife as to their origin. The old and popular belief was that which attributed their treelessness to the annual burning of the grass by the Indians. But the prairies present other phenomena which the annual burning fails to explain. Besides, the treelessness remains in regions where the burnings have ceased. And, lastly, the treeless prairies were not the only regions burned by the Indians. And if they were, it seems more likely that the Indian burned the rank grasses because the region was treeless, than that the region became treeless from the burning of such vegetation as flourishes in the shade of a forest.

It has sometimes been suggested that the region was originally forest-covered, and that the southern cane flourished in such luxuriance amongst the trees as to rob them of their moisture and nourishment, and thus cause their extinction. The cane, having deprived itself of the protecting shade of the forest, was in turn scorched out by the rays of the summer sun. This theory is every way unsatisfactory.

With others, the absence of trees is to be attributed to the dryness of the atmosphere-and consequently of the soil-at certain seasons of the year. It can not be doubted that the treeless plains of the far West, and also other regions, have failed to produce arboreal growths through an insufficient supply of moisture. Still other treeless regions are such from an excess of saline constituents in the soil. But all such regions have nothing in common with the prairies of Illinois except their treelessness. The topog