Chap. VII. 
INSTINCT. 
207 
CHAPTEK VIL 
Instinct. 
Instincts comparable with habits, hut 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 mentaP 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. 
