From the western border of northern France, through Belgium, North Germany, and Russia, almost to the eastern confines of Siberia, extends a broad plain rarely interrupted by low chains of hills, and just as rarely affording fitting soil for extensive growth of wood, which, on the whole, confines itself to the more favorable soil moistened by the vicinity of rivers. Along the southern border of this plain extends a chain of hills and mountains, now projecting forward like capes into the broad surface, now retreating into broad or narrow creeks, the coast of a sea formerly covering the whole plain. Over all this endless expanse has one single species of plant established an almost exclusive predominance, the heath, which has lent its name to those tracts of land. Conditions similar to those which produce the distinction between the pine barrens and cypress swamps in North America are also active here to cause an essential difference. The great flatness of the ground, even geological conditions in many places, as where slight elevations of the land forming flat inclosed basins, prevent, in many situations, the free discharge of water, and the heath, backed by the special vegetation produced by the moisture, forms by the annual accumulation of vegetable matter, which in water only becomes to a certain degree carbonized or decomposed, those black masses of the remains of plants which as peat bear such an important part in the economy of the inhabitants. Thus, in various modes of distribution, alternate arid, dry sandy heaths with moist, spongy peat heaths or moors. On the margin of the latter, more rarely actually upon them, and on the heaths of Luneburg are often found splendid oaks, which, overshadowing one of those pleasant straw-thatched houses and thrown out by the background of the peculiar red tint of the glancing heather, produce a picturesque charm which would not have been expected here. With these great moors may be associated the peat moors of some of the higher mountain chains of the Brocken, the Röhn, and the Fichtel-Gebirge, and so on, and the so-called mosses of South Germany and Switzerland.