We shall, perhaps, best understand how instincts in a state of nature have become modified by selection by considering a few cases.
I will select only three, namely, * the instinct which leads the cuckoo to lay her eggs in other birds’ nests; * the slave-making instinct of certain ants; * and the cell-making power of the hive-bee:
these two latter instincts have generally and justly been ranked by naturalists as the most wonderful of all known instincts.