It is wrong for us to say that those things with which an animal grows and by which it reaches completion are not parts of it; but the leaves and everything that is found in a pla are parts of that plant, although they are not determined and are gradually shed; for the antlers of a stag and the hair of certain animals, and the fur of certain of those which hibernate in hollows underground, fall off, and this process resembles the shedding of leaves.