Not one of our domestic animals can be named which has not in some country drooping ears; and the view which has been suggested that the drooping is due to disuse of the muscles of the ear, from the animals being seldom much alarmed, seems probable.
Many laws regulate variation, some few of which can be dimly seen, and will hereafter be briefly discussed.

I will here only allude to what may be called correlated variation.

Important changes in the embryo or larva will probably entail changes in the mature animal.

In monstrosities, the correlations between quite distinct parts are very curious; and many instances are given in Isidore Geoffroy St.Hilaire's great work on this subject.

Breeders believe that long limbs are almost always accompanied by an elongated head.