| Comparison with 1861 | 
| 
 | 
| ON THE 
ORIGIN OF SPECIES. 
—  —  —  —   — — | — — 1861 |  | — 1859 |  | — — — 1860 |  | OMIT 1866 1869 |  | OMIT 1872 | 
 | 
| INTRODUCTION. | 
|  | 
| 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 inhabitants of that continent.  These 
 facts,| organic beings inhabiting 1861 1866 1869 1872 |  | inhabitants of 1859 1860 | 
as will be seen in the latter chapters of this volume, seemed| facts, 1861 1866 1869 1872 |  | facts 1859 1860 | 
to throw some light on the origin of species— that mystery 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 allowed 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 probable: 
from that period to the present day I have steadily pursued the same object.  I hope that I may be excused for entering on these personal details, as I give them to show that I have not been hasty in coming to a decision.| as will be seen in the latter chapters of this volume, seemed 1861 1866 1869 1872 |  | seemed to me 1859 1860 | 
 | 
|  | 
| My work is now nearly 
finished; but as it will take me two or three 
more years to complete it, and as my health is far from strong, I have been urged to publish this Abstract.  I have more especially been induced to do this, as Mr. Wallace,  who  is  now  studying  the | 
 
  
  
| ON THE ORIGIN OF 
 SPECIES.| ON THE 1859 1860 1861 1866 1869 |  | ON THE1872 | 
—| SPECIES. 1859 1860 1861 1869 1872 |  | SPECIES, 1866 | 
—| — 1859 1860 1861 1872 |  | —1866 1869 | 
—| — 1859 1860 1861 1872 |  | —1866 1869 | 
—| — 1859 1860 1861 1872 |  | —1866 1869 | 
—| — 1859 1860 1861 |  | —1866 1869 |  | —1872 | 
| — 1859 |  | — — — 1860 |  | — — 1861 |  | OMIT 1866 1869 |  | OMIT 1872 | 
 | 
| INTRODUCTION. | 
|  | 
| WHEN on board H.M.S. 'Beagle,' as naturalist, I was much struck with certain facts in the distribution of the 
 inhabitants of South America, and in the geological relations of the present to the past inhabitants of that continent.  These 
 facts| inhabitants of 1859 1860 |  | organic beings inhabiting 1861 1866 1869 1872 | 
seemed to me| facts 1859 1860 |  | facts, 1861 1866 1869 1872 | 
to throw some light on the origin of species— that mystery 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 allowed 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 
 probable:| seemed to me 1859 1860 |  | as will be seen in the latter chapters of this volume, seemed 1861 1866 1869 1872 | 
from that period to the present day I have steadily pursued the same object.  I hope that I may be excused for entering on these personal details, as I give them to show that I have not been hasty in coming to a decision.| probable: 1859 1860 1861 1866 1869 |  | probable; 1872 | 
 | 
|  | 
| My work is now 
 nearly finished; but as it will take me 
 two or three| nearly 1859 1860 1861 1866 1869 |  | (1859) nearly 1872 | 
more years to complete it, and as my health is far from strong, I have been urged to publish this Abstract.  I have more especially been induced to do this, as Mr. 
 Wallace,| two or three 1859 1860 1861 1866 1869 |  | many 1872 | 
who| Wallace, 1859 1860 1861 1866 1869 |  | Wallace,1872 | 
is| who 1859 1860 1861 1866 1869 |  | who1872 | 
now| is 1859 1860 1861 1866 1869 |  | is1872 | 
studying| now 1859 1860 1861 1866 1869 |  | now1872 | 
the| studying 1859 1860 1861 1866 1869 |  | studying1872 | 
| the 1859 1860 1861 1866 1869 |  | the1872 | 
 |