204 THE GENESIS OF SPECIES. [Chap. 



Tliougli Mr. Darwin lias not as yet expressly advocated 

 this view, yet some remarks made by him a}>|iear to show 

 his disposition to sympathize with it. Thus in his M'ork 

 on " Animals and Plants under Domestication," ^ he asserts 

 that " the savages of Australia and South America hold the 

 crime of incest in abhorrence ; " but he considers that this 

 abhorrence has probably arisen by "Natural Selection," 

 tiie ill eft'ects of close interbreeding causing the less numer- 

 ous, and less healthy ollspring of incestuous unions to dis- 

 appear by degrees, in favor of the descendants (greater 

 both in number and strength) or individuals who naturally, 

 from some cause or other, as he suggests, preferred to mate 

 with strangers rather than with close blood-relations; this 

 preference being transmitted and becoming thus instinc- 

 tive, or habitual, in remote descendants. 



But on Mr. Darwin's own ground, it may be objected 

 that this notion fails to account for " abhorrence " and 

 "moral reprobation ;" for, as no stream can rise higher 

 than its source, the original " slight feeling " which was 

 iiseful would have been perpetuated, but would never have 

 been augmented beyond the degree requisite to insure this 

 beneficial preference, and therefore would not certainly 

 have become magnified into " abhorrence." It will not do 

 to assume that the union of males and females, each pos- 

 sessing the required " slight feeling," must give rise to off- 

 spring with an intensified feeling of the same kind ; for, 

 apart from reversion, Mr. Darwin has called attention to 

 tlie unexpected modifications which sometimes result from 

 the union of sunllarb/ constituted parents. Thus, for ex- 

 ample, he tells us : ' "If two tojvknotted canaries are 

 matched, the young, instead of having very fine loj)-knots, 

 are generally bald." From examples of this kind, it is fair, 

 on Darwinian i)rinciples, to infer that the imion of j)arents 



« Vol. ii., p. 122. 



^ "Animals and Plants under Domestication," vol. i, p. 296. 



