268 GEOGRAPHY OF PLANTS. 



and which lies a little further south than Congo, has yet no 

 plants, which are found in those last named regions ; (Rox- 

 burgh's List of Plants seen in the Island of St Helena, Ap- 

 pend, to Beatson's Island of St Helena.) Japan has a great 

 many plants common to southern Europe, which, however, 

 are not found in these regions of Asia that lie under the same 

 latitude. 



395. 

 We must further remark, that the eastern countries of the 

 old world, and the eastern shores of America, as far as the 

 Alleghany Mountains, have a much lower temperature than 

 the western regions ; or that it is always colder in Siberia 

 and the north-east of Asia, than under the same latitude in 

 Europe; and that even Petersburgh is colder than Upsal, 

 and Upsal than Christiania, although they all three lie in the 

 60th degree of north latitude. In North America the differ- 

 ence is still greater, and there are commonly fifteen degi'ecs of 

 Fahrenheit's thermometer between the temperature of the east 

 and west coast. It hence happens tliat many plants, which in 

 Norway grow under the polar circle, scarcely reach the 60th 

 degree on the limits between Asia and Europe. To this class 

 i)elong the Silver-fir, Mountain-asli, Trembling Poplar, 

 Black Alder, and Juniper. Even in the temperate zone, 

 the vegetation of many trees ceases sooner in the east than in 

 the west. In Lithuania and Prussia, under the 53d degree, 

 neither Vines, nor Peaches, nor Apricots thrive ; at Jeast 

 their fruit does not ripen, as also happens in the middle of 

 England. The most remarkable example of this great differ- 

 ence of temperature is furnished by the Mesp'ilus Japonica^ 

 which grows at Nanga sacki and Jeddo, under the 33d and 

 36th degrees of N. Lat., and which also grows in the open air 

 in England, under the 52d degree of N. Lat., when it is 

 planted against a wall, (Botanical Register, vol. v.) 



396. 

 The same degrees of latitude, in the southern and northern 

 hemif=phcfc, arc connected with very different temperatures, 



