ranunculus bullatus, capparis rupestris, scrophularia bicolor, heliotropium bocconi, mandragora autumnalis, senecio chrysanthemifolius, daphne gnidium, spartium infestum, solanum sodomæum, ricinus africanus, smilax aspera, euphorbia, linaria, &c. The region of woods extends to 6,500, the oak and chestnut ceasing at 4,350 feet, and pinus sylvestris at the limit of the region. The region of shrubs ceases at 8,125 feet, and contains bushes of juniperus, berberis, betula, and fagus. The region of grasses ceases at 9,750 feet, and of cryptogamic plants at 10,000 feet.

RELATIONS.-Rhododendron, and some few others, carry our associations to the alpine regions of Asia and America, to lesser heights in China, and to some northern latitudes. Sempervivum abounds in species in the Canaries, yet on Ætna not a trace of it exists, but is replaced by sedum, which is equally numerous, but has no existence in the Canaries.

XLVI. THE CENTRAL EUROPE REGION.

EXTENT. That portion of the centre of Europe to the north of the southern chain of mountains is distinguished for a certain individuality in its vegetation, and the extensive cultivation of wheat. The southern limit is bounded by the Alps and the Carpathians to the Caspian Sea, and the Pyrenees and the Cevennes, thus excluding a portion of the south of France. To the north it includes Denmark, and a part of the south extremes of Sweden and Norway, and is separated from the Volga Region by a line commencing in the Baltic on the coast in 55o N. lat., and traversing the southern provinces of Russia to the sea of Azof. Its northern limit is in the vicinity of the

boundary of acer, pseudo-platanus, morus nigra, populus alba, p. nigra, pyrus malus, the vine and the chestnut; and the region generally may be regarded as that portion of Europe where wheat is most advantageously cultivated for food, to the north soon yielding to rye, and to the south to Indian corn and rice. Wheat is stated to be most profitably cultivated between 35° and 50° N. lat., and to cease entirely at 60° or 62°. The British islands complete the region.

PHYSICAL CHARACTERS.-According to Balbi, the surface of Europe presents several remarkable geographical features. Its centre consists of an extensive plain of considerable productiveness, and to the north in Russia it rises to a broad table-land of about 1,150 feet of elevation. Another important table-land occupies the centre of Spain, having an elevation of 2,300 feet, that of the Jura Alps attains from 1,750 to 3,850 feet, and another in Piedmont from 600 to 2,000 feet. But a far greater diversity is imparted by the several mountain chains of the Pyrenees, the Alps, the Carpathians, the Apennines, and the Dofrines, which considerably modify the climate and the character of the vegetation. Besides there are several valleys which serve to guide certain rivers to the ocean, and which are pre-eminent both for their beauty and fertility. Of these the most distinguished are the valleys of the Lower Danube, the Rhine, the Drave, and the Po. Formerly, by far the greater portion of the surface was covered with forest, much of which has been gradually removed by cultivation, but very extensive tracts in Russia and Poland are still in this state, and throughout Europe generally a good deal of forest still remains. On the whole, the soil is good and fruitful, but there are spots consisting of little else than rocks, or where the occasional invasion of the sea renders it unserviceable, or where bog, morass, or heath exists, to

the exclusion of cultivation, as in the countries south of the Baltic.

CLIMATE.-Malte-Brun and Balbi assign to Europe three well-defined climates; the Atlantic distinguished for its even temperature, and its moisture; the climate of the north-west of Europe being one of extremes of temperature: and the climate of the south, which, with its higher temperature, holds a middle station between the two others. Aware, however, that this division very imperfectly expressed all the important features, a further seven-fold one was proposed. Europe is so situated, between extensive seas on one side and a large mass of land and range of mountains on the other, that it cannot fail to be greatly governed by their influence over climate, and to offer some variety. Compared with other climates of a similar latitude, it will be found to be mild, less exposed to vicissitudes, and that vegetation attains a higher northern station. Between the west and east portions there are certain differences. The mean heat may be nearly the same through the same parallel, but the distribution in the seasons will be different. On the west side, the climate being equable, the range throughout the year is not great, and the mean of the summer and winter months will not be in excess; the atmosphere is also moister, and the number of rainy days greater. On the east side, however, the mean of these two seasons is prone to extremes, and to take respectively higher and lower stations. Whatever differences occur in the mean heat of the year will be in favour of the eastern portions. The result of this on vegetation is, that plants which prefer a climate free from extremes, and that move with the mean temperature, will take a higher northern station on the eastern side, as is visible in some of the plants of Norway and Sweden, the apple for instance; and those which revel in a hot summer, and are indifferent to

the extremes of winter, will be found occupying a limit gradually extending towards the north-east.

In the Central Europe Region, the circumstances of the climate are less strongly marked. The mean varies from 48° to 54°, and the usual annual range from 28° to 83°. The atmosphere is often much loaded with moisture, and the rainy days are nearly half the total to the year, though the quantity of rain which falls does not exceed from 22 to 30 inches. The mean hydrometric state of the atmosphere is four or six degrees below the mean temperature. In a climate so clouded, the power of the sun's rays over vegetation must be supposed to fall far short of their effects in lower and more brilliant latitudes.

FLORA. The indigenous productions are those of a temperate latitude. The climate holding a middle station, the plants of the south wander here, and those of the north do not find it ungenial; it has thus a large proportion of species for the extent of surface, and the more important groups of plants are freely represented. The region will therefore display, with a number of species, also a number of genera and families, the proportions of the latter to the former bring greater than usual. In the forest trees, however, the number of species as compared with other regions is singularly small, and genera extensively represented elsewhere have here often only solitary species. Nearly all have deciduous leaves, and though grasses have not an important numerical relation to the flora, they flourish in great luxuriance. These trees often manifest a partiality to particular soils, and in the forest, which clothes a larger portion of Poland, the oak, yew, ash, poplar, chestnut, and willow, are found on the clayey soil, whilst the pine and the fir occupy exclusively the sandy soil. Inconspicuous flowers prevail greatly, as might be expected where amentaceous and coniferous plants are so numerous, but in other

regions it is not unusual to have an intermixture of attractive flowers even in the trees, such as is not seen here. The details of the region may be sought for in ranunculaceæ, cruciferæ, caryophylleæ, geraniaceæ, saxifrageæ, leguminosa, particularly the section vicieæ, rosaceæ, stellatæ, compositæ, boragineæ, ericaceæ, gentianeæ, labiatæ, scrophularineæ, polygoneæ, chenopodeæ, the families of amentaceæ, orchidaceæ, junceæ, cyperaceæ, gramineæ, and a large proportion of the cryptogamic families.

Umbelliferæ have a slight preponderance over other regions, as will be seen in their distribution. The total number of species is 1,009, but the duplicate habitats are here included. In the Central Europe Region there are represented 172 species; Danube Region, 161; Italy Region, 152; Asia Minor Region, 90; Spain Region, 82; Barbary Region, 69; South Africa Region, 63; Iroquois Region, 61; Volga Region, 53; Siberia Region, 50; Chili and Peru Region, 45; New South Wales Region, 29; Paraguay Region, 19; Patagonia Region, 10; other regions, 216. They are here found to exist in far greater numbers in the northern hemisphere, and particularly in Europe. In the latter they are most densely assembled in the central, southern, and south-eastern portions, whence we may infer their partiality for a warm temperate climate, for warm summers and extremes in the seasons rather than the reverse, and lastly, for an atmosphere tolerably supplied with moisture. A few species cling to Western Europe along the shores of the Atlantic, and are not found in the eastern countries. Some have a partiality for elevated stations in the Pyrenees, Alps, Andes, and Mexican highlands, and the Asia Minor Region derives its species in great part from Caucasus.

France is chiefly included in this region; it has an area of 200,925 square miles, and 5,966 species; or, in the proportion of one species to about 34 square miles.