ripening of the former. At the more pointed free end of the acorn is a queer little knob, which is hard and dry, and represents the mummified remains of what was the stigma of the flower, and which lost its importance several months previously, after receiving the pollen.
The outer hard coat of the acorn is a tough, leather-brown polished skin, with fine longitudinal lines on it, and it forms the outer portion of the true covering of the fruit, called the pericarp (Fig. 2,p). On removing it we find a thin, papery membrane inside, adhering partly to the above coat and partly to the seed inside. This thin, shriveled, papery membrane is the inner part of the pericarp, and the details of structure to be found in these layers may be passed over for the present with the remark that they are no longer living structures, but exist simply as protective coverings for the seed inside.
The centre of the acorn is occupied more or less entirely by a hard brown body—the seed—which usually rattles about loosely on shaking the ripe fruit, but which was previously attached definitely at the broad end. A similar series of changes to those which brought about the separation of the acorn from the cup—namely, the shriveling up of the tiny connecting cords, etc.—also caused the separation of the seed from the pericarp, and we may regard the former as a distinct body.
Its shape is nearly the same as that of the acorn in which it loosely fits, and it is usually closely covered