EXCURSIONS OF AN EVOLUTIONIST 



nous there. A comprehensive survey of the dis- 

 tribution oflife all over the globe confirms this 

 conclusion, and shows that by no assumption 

 of a special act of creation can the peculiar fea- 

 tures of the Galapagos flora and fauna be ex- 

 plained. The only way in which to account for 

 these features is to suppose that the archipelago 

 has been peopled by migrations from the near- 

 est mainland. This explains why the creatures 

 there are most like the creatures of Ecuador and 

 Peru, and it also explains why the only indige- 

 nous animals to be found there are such as could 

 have flown or been blown thither, or such as 

 could have been ferried thither on floating vege- 

 tation. 



But if all this be true and to-day no com- 

 petent naturalist doubts it a conclusion of 

 vast importance immediately follows. If the 

 Galapagos plants and animals are descended 

 from ancestors that migrated thither from the 

 continent, they have been modified during ages 

 of residence in the islands, until they have come 

 to differ specifically, and in many cases generi- 

 cally, from their collateral relations on the main- 

 land. And this amounts to saying that species 

 are not fixed, but mutable, that every distinct 

 form of plant and animal was not originally 

 created with its present attributes, but that some 

 forms have arisen from the modification of an- 

 cestral forms. 



