382 



GEOGRAPHICAL DISTRIBUTION AND 



[Ch. XL. 



tlie influence of climate on the character of the vegetation 

 could hardly have escaped their observation. 



Antecedently to investigation, there was no reason for 



esuminor 



hemispher 



in the same latitude ; nor that the plants of the Cape of 

 Good Hope should be unlike those of the south of Europe ; 



— dissimilar . ^^^ 



supposition would have seemed more probable, and we might 

 have anticipated an almost perfect identity in the plants 

 which inhabit corresponding parallels of latitude at equal 

 heights above the sea. The discovery, therefore, that eacli 

 separate region of the globe, both of the land and water, is 

 occupied, in the vegetable as well as in the animal world, by 

 distinct groups of species, and that most of the exceptions to 



p-eneral rule are referable to disseminatin 

 )eratioii, is eminentlY calculated to i3repar( 



t) 



with favour any hypothesis respecting the first introduction 

 of species which may be reconcilable with such phenomena. 



Botanical regions. — Humboldt was among the first to pro- 

 mulgate philosophical views on the distinctness of the vegetable 

 productions of different regions of the globe. Every hemi- 

 sphere, he said, is inhabited by different species of plants, 

 and it is not by the diversity of climates that we can attempt 

 to explain why equinoctial Africa has no Laurinese, and 



New World 



Heaths 



found only in the southern hemisphere. 



We 



that a small number of the 



families of plants, for instance, the Musacese and the Palms, 

 cannot belong to very cold regions, on account of their in- 



import 



Melastomas 



allied to the Myrtles) vegetates north of the parallel of 

 thirty degrees ; or why no rose-tree belongs to the southern 

 hemisphere. Analogy of climates is often found in the two 

 continents without identity of productions .'t 



Massachusetts north of Boston; but this 



•^ The common heath {Erica vulgaris, 



L.) has, since Humboldt wrote, been case is quite exceptional. 



found growing wild in one spot in 



t Pers. Nar., vol. v. p. 180. 



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