DARWINISM. 17 



All that lie does, however miraculous it may seem, can 

 only be done under her conditions, and by the means 

 which she supplies. In Artificial Selection man does 

 but take advantage of the natural laws of Inheritance 

 and Variation, and while he is seeking by means of 

 these to produce one alteration, Nature herself is pro- 

 ducing perhaps a hundred others. For, by the law of 

 Correlation, when one part changes, some other or others 

 almost inevitably change with it. Whether it be 

 shortening the beak of a pigeon or lengthening the 

 neck of a giraffe that is in question, Nature takes care, 

 along with the change, to make other adaptations of the 

 structure in the creature's interest under its altered 

 circumstances. Surely, the working of this principle 

 of Correlation indicates a far-sighted Providence of 

 the results, the disastrous monstrosities, that would 

 otherwise have sprung from the law of Variation. 



Man's efforts are considerably limited, moreover, by 

 the law of Reversion. Now, supposing many differing 

 species to be descended, as we maintain, from common 

 ancestors, what ought to be the observable effects of this 

 law ? Evidently, we should expect the character of one 

 species now and then to appear in species allied to it, or 

 species of kindred origin to vary in the same manner. 

 In accordance with such an expectation, we find the 

 horse and the ass sometimes assuming the stripes of 

 the quagga and the zebra; certain varieties of the 

 pigeon, the fowl, the turkey, the canary-bird, the duck, 

 and the goose, all have top-knots or reversed feathers on 

 their heads ; one kind of melon resembles a cucumber in 



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