16 EVOLUTION 



common descent of species. ... In July 

 (1837) I opened my first notebook for facts in 

 relation to the Origin of Species, about which 

 I had long reflected, and never ceased work- 

 ing for the next twenty years. . . . Had been 

 greatly struck from about the month of pre- 

 vious March on character of South American 

 fossils, and species on Galapagos Archipelago. 

 These facts (especially latter) origin of all my 

 views." 



This interesting biographic fact, that what 

 Darwin saw on the Galapagos Islands and 

 elsewhere on his journeyings was (or at least 

 seemed to him) the origin of all his views, 

 justifies us in giving precedence to the "evi- 

 dences" of evolution that have come from 

 his and other explorations. 



The Galapagos Islands. — Let us take 

 the case of these islands (some six hundred 

 miles west of the coast of South America), 

 which impressed Darwin so much when he 

 visited them in 1835. What exactly was it 

 that impressed him? He found that each 

 island had its own distinctive animal popu- 

 lation, especially of reptiles and birds. And 

 yet the species in one island were the counter- 

 parts of those in another, and almost all had 

 their counterparts in the adjoining parts of 

 the continent. What a riddle indeed — unless 

 it meant that the corresponding species on 



