of the Galapagos Archipelago. 



259 



of intercourse, especially atmospheric storms, between the several islets, and 

 argues no physical peculiarity or want of vigour in the species themselves. 

 Supposing all the species now inhabiting the Galapagos to be collected on a 

 continuous surface, equalling in area the aggregate of the islets forming that 

 archipelago, then would the Flora lose much of its characters ; the strife with 

 its neighbours for position, which marks all stages of the life of any two or 

 more contiguous plants, would terminate in a few replacing the many, and the 

 introduced species bearing a greater proportion to the indigenous, whilst the 

 individuality of the Flora would thus be lessened in degree or wholly de- 

 stroyed. It must be admitted, that the first steps towards ensuring the conti- 

 nuance of many species in a given area, are to isolate them, and to cut off the 

 means of migration ; exactly as in a garden the plants are protected from en- 

 croachment mechanically, and the seeds of the more volatile collected betimes, 

 to prevent a like effect being naturally brought about. 



Though, however, this in some degree explains why the florulae of the 

 islets should be distinct in character, it can give no clue to the representation 

 of species amongst them ; which representation, whether it be regarded in the 

 light of the whole group bearing the imprint of America, with but few of the 

 productions of that continent, or of the several islets each individually distinct 

 combining to form an harmonious whole, is a mystery which it is my object 

 to portray, but not to explain ; and I shall proceed to show the amount of this 

 difference, and its relation to the physical features of the islets. 



The following table shows the amount of peculiarityin each island of flowering 

 plants and ferns, and the proportion confined to itself; those common to itself 

 and one or more other islets ; and such as are found on the American continent. 



* I have excluded seventeen species from the flora of this islet, as being almost certainly introduced 

 with cultivation. 



VOL. XX. 



2 M 



