Professor Agassiz, in passing through a dense young spruce forest some years ago, on the south shore of Lake Superior, noticed that the ground was thickly strewn with fallen birch trunks, showing that their place had been but recently usurped by the spruce; and he supposed that the birch had first succumbed to the force of the winds, and the spruce promptly taken its place, since, as a general rule, an evergreen growth succeeds a deciduous, and _vice versa._ We have any number of well authenticated facts similar to this stated by Professor Agassiz, but we cannot give place to them, in this connection, without greatly exceeding our limits.
Dr. Franklin B. Hough, in his recent "Report upon American Forestry," to which we have already referred, says: "It is not unusual to observe in the swamps of the northern states, an alternation of growth taking place without human agency. Extensive tracts of tamarack (_Larix Americana_) may be seen in northern Wisconsin that are dying out, and being succeeded by the balsam fir (_Abies balsamea_), which may be probably caused by the partial drainage of the swamps, from the decay or removal of a fallen tree that had obstructed the outlet." The writer of this work resided for a period of ten years or more in Wisconsin, and during that time traversed extensive portions of its territory, both before and after it became a state. As early as 1844, the extensive tamarack swamps of that region were manifestly dying out for the want of the proper nutritious elements in the soil, and the balsam fir rapidly taking its place, especially where the accumulations of soil, resulting from decayed vegetation, were favorable for its appearance. The drainage of the swamps had not been thought of at that time, nor had the swamps themselves been disposed of, to any considerable extent, by the federal government. They were subsequently granted to the state for educational purposes, and afterwards purchased up in the interest of speculative parties.
But the decay of the tamarack had really commenced long before population found its way, in any considerable numbers, into that section of the country; and the balsam fir had begun its usurpation, in many of the swamps, long prior to the advent there of the white man. Neither artificial drainage, nor accidental drainage, had anything to do with the appearance of the balsam fir, or the disappearance of the tamarack. The latter was manifestly dying out for the want of the proper nutriment, and the former coming in for the reason that the soil was chemically balanced for the development of its "primordial germs"--those everywhere implanted in the earth, to await the necessary conditions for their development and growth. The natural seeds of this balsam fir were not present in either the first, second, or third tamarack swamp in which this alternation of growth originally took place. The change commenced as soon as conditions favored, and not before. It is safe to say that, in none of these tamarack swamps, was there a single balsam fir cone, or a single chit to a cone, nor had there probably been for thousands of years, before the time when the first balsam fir made its appearance in that section. They came, as all primordial forests come, from germs, not from the seeds of trees. Universally, the germ precedes the tree, as the tree precedes the seed, in all vegetal growths, from the lowest cryptogam to the lordliest conifer of the Pacific slope. Otherwise, we should be logically driven back to an act of "specific creation," which the materialist stoutly rejects, and the Bible genesis nowhere affirms.