18 INTRODUCTION. 



it is published in the third vohime of the Journal of tliat So- 

 ciety, Sir C Lycll :uid Dr. Hooker, who both Icnew of my 

 work — tlic hitter having read my sketch of 1844 — honored me 

 by thinking it advisable to publish, with Mr. Wallace's excel- 

 lent memoir, some brief extracts from my manuscripts. 



This Abstract, -which I now publish, must necessarily be 

 imperfect. I cannot here give references and authorities for 

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

 some confidence in my accurac}'. No doubt errors Avill have 

 crept in, tliough I hope I have always been cautious in trust- 

 ing to good authorities alone. I can here give only the general 

 conclusions at which I have arrived, with a few facts in illustra- 

 tion, but which, I hope, in most cases will suffice. No one can 

 feel more sensible than I do of the necessity of hereafter pul> 

 lishing in detail all the facts, Avith references, on wliich 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 Avjiich facts cannot be adduced, 

 often apparently leading to conclusions directly opposite to 

 those at Avhich I have arrived. A fair result can be obtained 

 only by fully stating and balancing tlie facts and arguments 

 on both sides of each question ; and this is here imj^ossible. 



I much regret that Avant of space prevents my having the 

 satisfaction of acknowledging the generous assistance Avhich I 

 have received from A^ery many naturalists, some of them per- 

 sonally unknoAvn to me. I cannot, hoAvevcr, let this 02')por- 

 tunity pass Avithout expressing my deep obligations to Dr. 

 Hooker, Avho for tlie last fifteen years has aided me in CA'ery 

 [wssible Avay by his large stores of knoAAdedge and liis 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, l)ut had descended, like varieties, from other species. 

 Nevertlielcss, such a conclusion, even if Avell founded, Avould be 

 unsatisfactory, imtil it could be shoAvn how the innumerable 

 species inhabiting this Avorld haA'e been modified, so as to ac- 

 quin? that perfection of structure and coadaptation Avhich justly 

 excites our admiration. Naturalists continually refer to exter- 

 nal conditions, such as climate, food, etc., as the only possible 

 cause of variation. In one limited sense, as Ave shall hereafter 



