The unbroken forests had attained to their maximum density and strength of growth, and, as the older trees decayed and fell, they were succeeded by new shoots or seedlings, so that from century to century no perceptible change seems to have occurred in the wood, except the slow, spontaneous succession of crops. This succession involved no interruption of growth, and but little break in the "boundless contiguity of shade;" for, in the husbandry of nature, there are no fallows. Trees fall singly, not by square roods, and the tall pine is hardly prostrate, before the light and heat, admitted to the ground by the removal of the dense crown of foliage which had shut them out, stimulate the germination of the seeds of broad-leaved trees that had lain, waiting this kindly influence, perhaps for centuries. FORMATION OF BOGS. Two natural causes, destructive in character, were, indeed, in operation in the primitive American forests, though, in the Northern colonies, at least, there were sufficient compensations; for we do not discover that any considerable permanent change was produced by them. I refer to the action of beavers and of fallen trees in producing bogs, [Footnote: The English nomenclature of this geographical feature does not seem well settled. We have bog, swamp, marsh, morass, moor, fen, turf-moss, peat-moss, quagmire, all of which, though sometimes more or less accurately discriminated, are often used interchangeably, or are perhaps employed, each exclusively, in a particular district. In Sweden, where, especially in the Lappish provinces, this terr-aqueous formation is very extensive and important, the names of its different kinds are more specific in their application. The general designation of all soils permanently pervaded with water is Karr. The elder Laestadius divides the Karr into two genera: Myror (sing. myra), and Mossar (sing. mosse). "The former," he observes, "are grass-grown, and overflowed with water through almost the whole summer; the latter are covered with mosses and always moist, but very seldom overflowed." He enumerates the following species of Myra, the character of which will perhaps be sufficiently understood by the Latin terms into which he translates the vernacular names, for the benefit of strangers not altogether familiar with the language and the subject: 1. Homyror, paludes graminosae. 2. Dy, paludes profundae. 3. Flarkmyror, or proper karr, paludes limosae. 4. Fjalimyror, paludes uliginosae. 5. Tufmyror, paludes caespitosae. 6. Rismyror, paludes virgatae. 7. Starrangar, prata irrigata, with their subdivisions, dry starrungar or risangar, wet starrangar and frakengropar. 8. Polar, lacunae. 9. Golar, fossae inundatae. The Mossar, paludes turfosae, which are of great extent, have but two species: 1. Torfmossar, called also Mossmyror and Snottermyror, and, 2. Bjornmossar.