Audubon has given several remarkable cases of differences in the nests of the same species in the northern and southern United States.

Why, it has been asked, if instinct be variable, has it not granted to the bee "the ability to use some other material when wax was deficient?" But what other natural material could bees use? They will work, as I have seen, with wax hardened with vermilion or softened with lard.

Andrew Knight observed that his bees, instead of laboriously collecting propolis, used a cement of wax and turpentine, with which he had covered decorticated trees.

It has lately been shown that bees, instead of searching for pollen, will gladly use a very different substance, namely, oatmeal.

Fear of any particular enemy is certainly an instinctive quality, as may be seen in nestling birds, though it is strengthened by experience, and by the sight of fear of the same enemy in other animals.