40 NATURAL HISTORY OF PLANTS. 



tended themselves in the same way, and that the Flora of Berlin 

 has not acquired new species in a course of years? 



Plants that increase much by seed, and at the same time hy the 

 root, must be consequently the more widely dispersed ; it is not 

 therefore surprising, that several of these are found over all Eu- 

 rope, from one end of it to the other. Those plants too thai have 

 light seeds, which the wind can easily bear away, are more easily 

 disseminated than those whose seeds are heavy. Some plants there- 

 fore of the former description, have travelled from Lapland to the 

 extremest point of Italy, nay, even to the north of Africa. 



The northern parts of Asia possess many of the plants or Europe. 

 We see towards the north, the Northern Flora, towards the south, 

 the Austrian, and between these the Helvetian conspicuous. It 

 would seem that the European mountains had been sooner provided 

 with soil, and that this had been late in taking place on the Asi- 

 atic mountains, or that very little soil had covered the mountains 

 on the north-west coast of Asia. It is no wonder then if, even to 

 the Uralian and Altaic chains of mountains, the plains on this side 

 have few Asiatic, but many European plants. 



North America produces very many of the small European plants, 

 which, for the most part, are those of the Northern Flora. It is 

 therefore probable that at some former period, there had existed a 

 connexion between both the old and new worlds, which in later 

 times has been broken. 



In order to form a just idea of our proposition, with respect to 

 the dispersion of the vegetables of our globe, we must travel over 

 all the high primitive Alps, collect the Flora of each particular 

 mountain down to its bottom, and in the neighbouring rallies, but 

 we must not descend into the plains. Were Europe investigated 

 in this manner, we would be able to determine, according to the 

 number of plants found existing there, how the dispersion must 

 have happened, and how the plants of this or that chain of moun- 

 tains have found their way to the plains. 



The sea-shore does not always indicate the Flora of the interior. 

 Upon the coasts we often find plants that have been brought 

 from the neighbouring regions. For this reason Asia, Africa, and 

 America, within the tropics, possess many plants in common, which 

 they have obtained from the shores of the neighbouring countries. 

 But if we travel further ilito the interior of those parts of the world, 



