2 THE ORIGIN OF SPECIES 



This abstract, which I now publish, must necessarily be im- 

 perfect. I cannot here give references and authorities for my 

 several statements; and I must trust to the reader reposing some 

 confidence in my accuracy. No doubt errors may have crept in, 

 though I hope I have always been cautious in trusting to good 

 authorities alone. I can here give only the general conclusions at 

 which I have arrived, with a few facts in illustration, but which, 

 I hope, in most cases will suffice. No one can feel more sensible 

 than I do of the necessity of hereafter publishing in detail all the 

 facts, with references, on which my conclusions have been 

 grounded; and I hope in a future work to do this. For I am well 

 aware that scarcely a single point is discussed in this volume on 

 which facts cannot be adduced, often apparently leading to con- 

 clusions directly opposite to those at which I have arrived. A 

 fair result can be obtained only by fully stating and balancing 

 the facts and arguments on both sides of each question; and this 

 is here impossible. 



I much regret that want of space prevents my having the satis- 

 faction of acknowledging the generous assistance which I have 

 received from very many naturalists, some of them personally 

 unknown to me. I cannot, however, let this opportunity pass with- 

 out expressing my deep obligations to Dr. Hooker, who, for the 

 last fifteen years, has aided me in every possible way by his large 

 stores of knowledge and his excellent judgment. 



In considering the origin of species, it is quite conceivable that 

 a naturalist, reflecting on the mutual affinities of organic beings, 

 on their embryological relations, their geographical distribution, 

 geological succession, and other such facts, might come to the 

 conclusion that species had not been independently created, but 

 had descended, like varieties, from other species. Nevertheless, 

 such a conclusion, even if well founded, would be unsatisfactory, 

 until it could be shown how the innumerable species, inhabiting 

 this world, have been modified, so as to acquire that perfection of 

 structure and coadaptation which justly excites our admiration. 

 Naturalists continually refer to external conditions, such as 

 climate, food, etc., as the only possible cause of variation. In one 

 limited sense, as we shall hereafter see, this may be true; but it 

 is preposterous to attribute to mere external conditions, the struc- 

 ture, for instance, of the woodpecker, with its feet, tail, beak, and 

 tongue, so admirably adapted to catch insects under the bark of 

 trees. In the case of the mistletoe, which draws its nourishment 

 from certain trees, which has seeds that must be transported by 

 certain birds, and which has flowers with separate sexes absolutely 



