NOW "THE ORIGIN OF SPECIES" CAME 

 TO BE WRITTEN. 



[An extract from the autobiography of Charles Darwin, 

 in "The Life and Letters of Charles Darwin," New York, 

 D. Appleton & I 



From September, 1854, I devoted my whole 

 time to arranging my huge pile of notes, to ob- 

 serving and to experimenting in relation to the 

 transmutation of species. During the voyage 

 of the Beagle I had been deeply impressed by 

 discovering in the Pampean formation great 

 fossil animals covered with armour like that on 

 the existing armadilloes; secondly, by the 

 manner in which closely allied animals replace 

 one another in proceeding southwards over 

 the continent: and, thirdly, by the South 

 American character of most of the productions 

 of the Galapagos Archipelago, and more espe- 

 cially by the manner in which these differ slightly 

 on each island of the group, none of these islands 

 appearing to be very ancient in »a geological 

 sense. 



It was evident that such facts as these, as 

 well as many others, could only be explained 

 on the supposition that species gradually 

 become modified; and the subject haunted me. 

 But it was equally evident that neither the 

 action of the surrounding conditions, nor the 

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