LOCAL AND SPECIFIC VARIETIES OF INSTINCT. 



CHAPTEE XVI. 



Instinct (continued). 



Local and Specific Varieties of Instinct. 



I HAVE now shown that instincts may arise through the 

 influence of natural selection, or of lapsing intelligence, or of 

 both these principles combined ; and that even fully formed 

 instincts are liable to change when changing circumstances 

 require. The most striking evidence on this head, or that of 

 the mutability of fully formed instincts, is perhaps the 

 evidence given in the last chapter, showing the influence of 

 domestication both in obliterating the strongest of natural 

 and in creating the most fantastic of artificial instincts. But 

 inasmuch as we have previously seen that any considerable 

 change in the circumstances to which an instinct is appro- 

 priate, is apt to throw the machinery of that instinct out of 

 gear, the evidence of the mutability of instinct drawn from 

 the effects of domestication may be open to the criticism that 

 the changes produced are of an unnatural character, or due to 

 an impairment of the normal apparatus of instinct. I do not 

 myself think that if this criticism were raised it would be 

 one of any force, seeing that (domestication not only has the ^ 

 negative effect of impairing or destroying natural instincts, 

 but also, as I have said, the positive effect of creating artifi- 

 cial instincts. ) Still it is (desirable to supplement the evidence \j. 

 drawn from the facts of domestication with further evidence 

 drawn from the field of nature) for here, at least, no criticism 

 of the kind which I have suggested can be advanced. I pro- 

 pose, therefore, in this chapter to consider all the facts which 

 I have been able to collect, tending to show that among i 

 animals in a state of nature instincts undergo transformations | 

 which are precisely analogous to those that they undergo 



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