224 AFFINITIES AND GEOGRAPHICAL 



poet, but the warrior, the statesman, the philosopher, and the 

 man of affairs, and who, moreover, appear to have had the mild 

 and manly, the moral and impulsive parts of our nature, in the 

 finest balance. 



When the naturalists of modern times began to inquire into 

 the geographical distribution of plants and animals, they quickly 

 found that the prevalent notion of their dispersion from one 

 common centre was untenable. From facts observed by them, 

 they have latterly concluded that, so far from this being the 

 case, there are many provinces of the earth's surface occupied 

 by plants and animals almost wholly peculiar, and which must 

 accordingly have had a separate origin. Professor Henslow, 

 of Cambridge, speaks of no fewer than forty-five such provinces 

 for the vegetable kingdom alone. 



A botanical or zoological province is generally isolated in 

 some manner, either as an island in the midst of a wide 

 ocean, as, for example, St. Helena, or the Isle de Bourbon, 

 or as a portion of a continent separated from the rest either by 

 a range of high mountains, or by the boundaries of a climate. 

 It is also found that elevation of position comes to the same 

 effect with regard to vegetation as advance in latitude ; so 

 that, as we ascend a lofty mountain in a tropical country, we 

 gradually pass through zones exhibiting the plants of kinds 

 appropriate to temperate and arctic regions. Even the neigh- 

 bourhood of a salt marsh, however remotely placed amongst 

 grounds of a different kind, exhibits plants appropriate to such 

 a soil. 



Fewer distinct zoological regions are enumerated, but perhaps 

 only in consequence of imperfect observation. Here, however r 

 the evidences against communication of organisms from one re- 

 gion to another are even more decided. If, however, it was sur- 

 mised that the organisms of isolated regions had been commu- 

 nicated from other countries, and merely modified in their new 

 abodes, the disproof of the conjecture would be more positive 

 with regard to the zoology of the question than the botany. 

 For, while it might appear possible that seeds have been floated 

 even five hundred miles to a new soil like that of the Isle de 

 Bourbon, how can we account, by such a supposition, for the 

 existence there of bats, reptiles, and other animals, the pro- 

 genitors of which could never have swum so far for the sake of 

 a change of residence '? This island, be it remarked, is of 

 volcanic origin, and known to have become dry land at a com- 

 paratively recent period. 



