ORiam OF SPECIES. 



INTEODUCTIOK 



When on board H.M.S. ' Beagle,' as naturalist, I was 

 much struck with certain facts in the distribution of 

 the organic beings inhabiting South America, and in 

 the geological relations of the present to the past in- 

 habitants of that continent. These facts, as will be 

 seen in the latter chapters of this volume, seemed to 

 throw some light on the origin of species — that mys- 

 tery of mysteries, as it has been called by one of our 

 greatest philosophers. On my return home, it occurred 

 to me, in 1837, that something might perhaps be made 

 out on this question by patiently accumulating and 

 reflecting on all sorts of facts which could possibly 

 have any bearing on it. After five years' work I al- 

 lowed myself to speculate on the subject, and drew up 

 some short notes; these I enlarged in 1844 into a sketch 

 of the conclusions, which then seemed to me proba- 

 ble: from that period to the present day I have steadily 

 pursued the same object. I hope that I may be ex- 

 cused for entering on these personal details, as I give 

 them to show that I have not been hasty in coming to a 

 decision. 



