Comments on article ["Perception and instinct in lower animals", Nature 7 (1871): 377–8].
Explains his contention that "many of the most wonderful instincts have been acquired, independently of habit, through the preservation of useful variations of pre-existing instincts". Cites examples: sterile workers of several species of social insects have acquired different instincts; movements of tumbler pigeons. Speculates that "many instincts have originated from modification or variations in the brain".