CHAPTER VIII 

 Instinct 



Instincts comparable with habits, but different in their origin — In- 

 stincts graduated — Aphides and ants — Instincts variable — Do- 

 mestic instincts, their origin — Natural instincts of the cuckoo, 

 molothrus, ostrich, and parasitic bees — Slave-making ants — Hive- 

 bee, its cell-making instinct — Changes of instinct and structure 

 not necessarily simultaneous — DifBculties of the theory of the 

 Natural Selection of instincts — Neuter or sterile insects — 

 Summary. 



MANY instincts are so wonderful that their develop- 

 ment will probably appear to the reader a diflficulty 

 sufficient to overthrow my whole theory. I may 

 here premise, that I have nothing to do with the origin of 

 the mental powers, any more than I have ^vith that of life 

 itself. We are concerned only with the diversities of instinct 

 and of the other mental faculties in animals of the same class. 



I will not attempt any definition of instinct. It would be 

 easy to show that several distinct mental actions are com- 

 monly embraced by this term; but every one understands 

 what is meant, when it is said that instinct impels the cuckoo 

 to migrate and to lay her eggs in other birds' nests. An ac- 

 tion, which we ourselves require experience to enable us to 

 perform, when performed by an animal, more especially by a 

 very young one, without experience, and when performed by 

 many individuals in the same way, without their knowing 

 for what purpose it is performed, is usually said to be in- 

 stinctive. But I could show that none of these characters 

 are universal. A little dose of judgment or reason, as Pierre 

 Huber expresses it, often comes into play, even with animals 

 low in the scale of nature. 



Frederick Cuvier and several of the older metaphysicians 

 have compared instinct with habit. This comparison gives, 

 I think, an accurate notion of the frame of m-ind under 



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