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. It cell-making instinct Difficulties on the theory of the Natural Selection of instincts Neuter or sterile insects Summary. Frederick Cuvier and several of the older metaphysicians have compared instinct with habit. Several other points of resemblance between instincts and habits could be pointed out. As modifications of corporeal structure arise from, and are increased by, use or habit, and are diminished or lost by disuse, so author do not doubt it has been with instincts. No complex instinct can possibly be produced through Natural Selection, except by the slow and gradual accumulation of numerous, slight, yet profitable, variations. The canon of Natura non facit saltum applies with almost equal force to instincts as to bodily organs.