Chap. VII. INSTINCT. 207 



CHAPTEE VII. 



Instinct. 



Instincts comparable with habits, but different in their origin — 

 Instincts graduated — Aphides and ants — Instincts variable — 

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

 ostrich, and parasitic bees — Slave-making ants — Hive-bee, its 

 cell-making instinct — Difficulties on the theory of the Natural 

 Selection of instincts — Neuter or sterile insects — Summary. 



The subject of instinct might have been worked into the 

 previous chapters ; but I have thought that it would be 

 more convenient to treat the subject separately, espe- 

 cially as so wonderful an instinct as that of the hive- 

 bee making its cells will probably have occurred to 

 many readers, as a difficulty sufficient to overthrow my 

 whole theory. I must premise, that I have nothing to 

 do with the origin of the primary mental powers, any 

 more than I have with that of life itself. We are con- 

 cerned only with the diversities of instinct and of the 

 other mental qualities of animals within 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 under- 

 stands 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 should require 

 experience to enable us to perform, when performed by 

 an animal, more especially by a very young one, without 

 any experience, and when performed by many indivi- 

 duals in the same way, without their knowing for what 

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



