SOUTH WESTERN PARTS QF EUROPE. 39 



moist forests, in the other of dry hills, and warm 

 damp winters. All that are peculiar to dead putrid 

 wood, must of course be scarce in the South of 

 Europe. 



As the greater number of those plants which 

 are the most universal appear to be aborigines of 

 the North, hence towards the South they are less 

 frequent : and, indeed, plants of northern climates 

 adapt themselves with greater facility to the south- 

 ern regions than vice versa. Hence it is, that 

 plants, found in the greatest abundance in the 

 most southern parts of Europe, take their rise but 

 little farther towards the North. Nothing is more 

 common in the South of Spain and Portugal than 

 some species of Cistus, of which the North of 

 Spain contains but very few. 



This last observation proves, that the power of 

 naturalization in plants has its fixed boundaries. 

 Many plants growing with us in corn-fields are not 

 become spontaneous in the South of Europe ; 

 Centaurea Cyanus of our corn-fields, for instance, 

 is not to be met with in those parts. 



Several species of plants are not, indeed, so 

 universal as the above enumerated, but we find 



