THE VEGETABLE WORLD. 351 



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 these 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 

 enclosed basins, prevent, in many situations, the free dis- 

 charge of the 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 in- 

 habitants. Thus in various modes of distribution alternate 

 arid, dry Sandy Heaths with moist, spongy Peat Heaths or 

 Moors. On the margins of the latter, more rarely actually 

 upon them, a more or less healthy vegetation of Trees 

 settles, and on the heaths of Luneburg are often found 

 splendid Oaks, which, over-shadowing one of those pleasant, 

 straw-thatched houses and thrown out by the back-ground 

 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 Rohn and the Fichtel-Gebirge and so on, 

 and the so-called Mosses of South Germany and Switzer- 

 land. 



In another climate, in another zone of vegetation, exist 

 similar conditions, stretching across the extreme north of 



