Owing to great difference in elevation of the surface, there is much diversity in the production of Switzerland. In the valleys the summer heat is tropical, while the surrounding heights are robed in perpetual snow. “From the lowest level on the southern slope of the Alps, say about six hundred and fifty feet, where the lemon, the almond, and the fig ripen in the open air, and thence ascend to an elevation of nine thousand five hundred feet, where every vestige even of the most primitive artificial cultivation ceases, we might trace nearly every species of vegetable growth known in Europe.”[79] Cereals are grown up to three thousand six hundred feet; rye succeeds up to five thousand nine hundred feet in the Grisons, and to six thousand five hundred feet on the sunny slopes of Monte Rosa and Pontresina. Irrespective of exceptional cases we may say that cultivation ceases at three thousand nine hundred and fifty feet, and above this height all forms of vegetation are small and poor, consisting of low scrubs, stunted firs, and mournful larches. As a general rule, vegetation reaches a higher point in eastern and southern Switzerland than in the northwest. It is therefore not the absolute height which determines the boundary of the growth of plants so much as the disposition and form of the mountains and valleys. Another point affecting materially the whole phytological covering of a country is the nature of the geological formation on which the plants grow. One-half of the country lies above the region of agriculture. The total area of land under cultivation in Switzerland is, in figures, 5,378,122 acres; of which, 1,715,781 acres, or 31.9 per cent., are meadow land, and 1,962,656 acres, or 36.5 per cent., are pasturage. The arable land covers an area of 1,533,093 acres, or 28.5 per cent., of the whole; vineyards 87,714 acres, or 1.6 per cent.; while the ground devoted entirely to gardening purposes may be estimated at about 78,870 acres, or 1.5 per cent. The area of cultivated land is steadily diminishing, as the meadows prove more remunerative. Good arable land, being so limited, commands a very high price, from $300 per acre to $1500 and $2000 per acre for choice vineyard lands. About one-half of the arable land is sown in grain; the remainder being used for potatoes, turnips, green maize, clover, vetch, etc. Both the federal and cantonal governments have shown an active interest in fostering and promoting the agricultural prosperity of the country; and an agricultural bureau is attached to one of the federal departments at Bern. The cultivation of the grape is closely identified with Swiss agricultural interests, and with few exceptions the hill-sides on the Lake of Geneva have been since the earliest periods of history planted with the generous vine. There exist records to prove that some of these vineyards have been bearing uninterruptedly for five hundred years. The reader will readily suppose that the materials have been often renewed.