280 HISTORY OF THE 



and tlieir distribution from one point over the surface of the 

 earth. 



406. 



It betrays very limited ideas respecting the laws of vege- 

 tation to suppose, that all the plants upon the face of the 

 earth, which require such different climates, such a differ- 

 ent constitution of the mountain-rocks, so various a composi- 

 tion of soil and of water, could ever have been assembled upon 

 one and the same high mountain ridge. All testimonies, indeed, 

 confirm the supposition, that the human race, and the domes- 

 tic animals, descended from the high mountain plains of cen- 

 tral Asia, between the 27th and 44th degrees of N. Lat. We 

 may also conjecture, that the different kinds of grain grow 

 M'ild in these latitudes, as it is also probable that the domes- 

 tic animals are there found in their native state. But the in- 

 numerable other wild growing plants, of all quarters of the 

 globe, which are so frequently confined to a single island, or 

 to a single circle of the continent, cannot possibly have their 

 native seats in those regions ; otherwise the remains of that 

 vegetation which is now dispersed over the whole face of the 

 earth, would be found in Northern India and Persia, in Thi- 

 ])ct, and in the Mogul empire. It is physically impossible, 

 that plants, which in Germany grow only upon calcareous 

 soils, or upon basalt and other peculiar mountain rocks, could, 

 at an early period, have flourished upon the primitive granite 

 and gneiss of the Himalaya Mountains. 



407. 



As little can we assent to the opinion of those who consider 

 the high mountain tracts as so many birth-places, or foci of 

 vegetation, and of the neighbouring Floras. We admit, that 

 when a particular moinitain chain stretches into the level 

 country beneath it, its peculiar plants will also appear in the 

 low land. The flcetz limestone of central Germany confirms 

 this conclusion in the strongest manner. But when this is 

 not the case, the low country never partakes of the Flora of 

 the neighbouring mountains. Otherwise, Scsrll Hipjwma- 



