ISLANDS to THOSE OF THE MAINLAND. 393 



that very closely, as we know from Dr. Hooker's account, to 

 those of America : but on the view that this island has been 

 mainly stocked by seeds brought with earth and stones on 

 icebergs, drifted by the prevailing currents, this anomaly 

 disappears. New Zealand in its endemic plants is much 

 more closely related to Australia, the nearest mainland, than 

 to any other region : and this is what might have been 

 expected ; but it is also plainly related to South America, 

 which, although the next nearest continent, is so enormously 

 remote, that the fact becomes an anomaly. But this diffi- 

 culty partially disappears on the view that New Zealand, 

 South America, and the other southern lands, have been 

 stocked in part from a nearly intermediate though distant 

 point, namely, from the Antarctic Islands, when they were 

 clothed with vegetation, during a warmer tertiary period, 

 before the commencement of the last Glacial period. The 

 affinity, which, though feeble, I am assured by Dr. Hooker is 

 real, between the flora of the south-western corner of Aus- 

 tralia and of the Cape of Good Hope, is a far more remark- 

 able case ; but this affinity is confined to the plants, and will, 

 no doubt, some day be explained. 



The same law which has determined the relationship be- 

 tween the inhabitants of islands and the nearest mainland, 

 is sometimes displayed on a small scale, but in a most inter- 

 esting manner, within the limits of the same archipelago. 

 Thus each separate island of the Galapagos Archipelago is 

 tenanted, and the fact is a marvellous one, by many distinct 

 species ; but these species are related to each other in a very 

 much closer manner than to the inhabitants of the American 

 continent, or of any other quarter of the world. This is 

 what might have been expected, for islands situated so near 

 to each other would almost necessarily receive immigrants 

 from the same original source and from each other. But 

 how is it that many of the immigrants have been differently 

 modified, though only in a small degree, the islands situated 

 within sight of each other, having the same geological 

 nature, the same height, climate, etc. ? This long appeared 

 to me a great difficulty : but it arises in chief part from the 

 deeply-seated error of considering the physical conditions of a 

 country as the most important ; whereas it cannot be disputed 

 that the nature of the other species with which each has to 

 compete, is at least as important, and generally a far more 

 important element of success. Now, if we look to the 

 species which inhabit the Galapagos Archipelago, and are 



