10 INTRODUCTION. 



constitution and climate. Still more surprising was the fact 

 that most of the inhabitants of each separate island in this 

 small archipelago were specifically different, though most closely 

 related to each other. The archipelago, with its innumerable 

 craters and bare streams of lava, appeared to be of recent origin ; 

 and thus I fancied myself brought near to the very act of 

 creation. I often asked myself how these many peculiar animals 

 and plants had been produced : the simplest answer seemed to 

 be that the inhabitants of the several islands had descended from 

 each other, undergoing modification in the course of their descent ; 

 and that all the inhabitants of the archipelago had descended 

 from those of the nearest land, namely America, whence colo- 

 nists would naturally have been derived. But it long remained 

 to me an inexplicable problem how the necessary degree of 

 modification could have been effected, and it would have thus 

 remained for ever, had I not studied domestic productions, and 

 thus acquired a just idea of the power of Selection. As soon 

 as I had fully realized this idea, I saw, on reading Malthus on 

 Population, that Natural Selection was the inevitable result of 

 the rapid increase of all organic beings ; for I was prepared to 

 appreciate the struggle for existence by having long studied the 

 habits of animals. 



Before visiting the Galapagos I had collected many animals 

 whilst travelling from north to south on both sides of America, 

 and everywhere, under conditions of life as different as it is 

 possible to conceive, American forms were met with — species re- 

 placing species of the same peculiar genera. Thus it was when 

 the Cordilleras were ascended, or the thick tropical forests pene- 

 trated, or the fresh waters of America searched. Subsequently 

 I visited other countries, which in all the conditions of life were 

 incomparably more like to parts of South America, than the 

 different parts of that continent were to each other ; yet in 

 these countries, as in Australia or Southern Africa, the traveller 

 cannot fail to be struck with the entire difference of their pro- 

 ductions. Again the reflection was forced on me that community 

 of descent from the early inhabitants or colonists of South America 

 would alone explain the wide prevalence of American types of 

 structure throughout that immense area. 



To exhume with one's own hands the bones of extinct and 



