Chap. XIV. RECAPITULATION. 459 



CHAPTEE XIY. 



Recapitulation and Conclusion. 



Recapitulation of the difficulties on the theory of Natural Selection 

 — Recapitulation of the general and special circumstances in its 

 favour — Causes of the general belief in the immutability of 

 species — How far the theory of natural selection may be 

 extended — Effects of its adoption on the study of Natural 

 history — Concluding remarks. 



As this whole volume is one long argument, it may be 

 convenient to the reader to have the leading facts and 

 inferences briefly recapitulated. 



That many and grave objections may be advanced 

 against the theory of descent with modification through 

 natural selection, I do not deny. I have endeavoured 

 to give to them their full force. Nothing at first can 

 appear more difficult to believe than that the more 

 complex organs and instincts should have been per- 

 fected, not by means superior to, though analogous 

 with, human reason, but by the accumulation of innumer- 

 able slight variations, each good for the individual pos- 

 sessor. Nevertheless, this difficulty, though appearing 

 to our imagination insuperably great, cannot be con- 

 sidered real if we admit the following propositions, 

 namely, — that gradations in the perfection of any organ 

 or instinct, which we may consider, either do now exist 

 or could have existed, each good of its kind, — that all 

 organs and instincts are, in ever so slight a degree, 

 variable, — and, lastly, that there is a struggle for exist- 

 ence leading to the preservation of each profitable 

 deviation of structure or instinct. The truth of these 

 propositions cannot, I think, be disputed. 



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