CHAPTER XIV 



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 ex- 

 tended — 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 serious 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 

 possessor. Nevertheless, this difficulty, though ap- 

 pearing to our imagination insuperably great, cannot 

 be considered real if we admit the following proposi- 

 tions, 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 existence leading to the preservation of each profit- 

 able deviation of structure or instinct. The truth of 

 these propositions cannot, I think, be disputed. 



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