Instincts comparable with habits, but different in their origin--Insticts graduated--Aphides and ants--Instincts variable--Domestic 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--Difficulties of the theory of the Natural Selection of instincts--Neuter or sterile insects--Summary
MANY instincts are so wonderful that their development will probably 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 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 per-