Chap. viii. Instinct. 205 



CHAPTEE VIII. 



Instinct. 



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

 graduated — Aphides and ants — Instincts variable — Domestic in- 

 stincts 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 —Difficulties of the theory of the Natural Selection of 

 instincts — Neuter or sterile insects — Summary. 



Many instincts are so wonderful that their development will pro- 

 bably appear to the reader a difficulty 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 with 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 commonly 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 action, which we ourselves require expe- 

 rience to enable us to perform, when performed by an animal, more 

 especially by a very young one, without experience, and when per- 

 formed by many individuals in the same way, without their knowing 

 for what purpose it is performed, is usually said to be instinctive. 

 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 mind under which an instinctive 

 action is performed, but not necessarily of its origin. How uncon- 

 sciously many habitual actions are performed, indeed not rarely in 

 direct opposition to our conscious will ! yet they may be modi- 

 fied by the will or reason. Habits easily become associated with 

 other habits, with certain periods of time, and states of the body 

 When once acquired, they ofteo remain constant throughout life 



