In this chapter Darwin discusses instincts such as the migration of birds or behavior of bees in a hive which are passed on to generations without their experience of having learned it themselves. Though Darwin at first admits difficulty in defining instance, he later defines it for his purposes as a habitual action that is inherited. Just as with the development of complex organs earlier, the development of complex instincts are produced by "the slow and gradual accumulation of numerous slight, yet profitable variations."
These instincts may help in the survival of the individual, or of the species.
