be measured accurately; it may be as short as a few hours or as long
as several days, but in all probability it is never longer than a
week. Although the element of time is uncertain the method of
transmission is well understood. Of its own accord the ovum can move
after fertilization no better than before; it is never capable of
moving itself. The active agent of transportation is the oviduct,
which has been fitted for this purpose with millions of short, hair-
like structures that project into its interior. These are closely set
upon the inner surface of the oviduct; their outer ends are free and
continually sway to and fro like a wheat field on a windy day; and by
their motion they create a current in the direction in which the ovum
should move, namely, toward the uterus. While passing through the
oviduct, the ovum has no attachment whatever to the mother, yet
development is going on all the time. It is thus made perfectly clear
that development is not directed by the parent. This independence of
the parent, though it continues to be one of the characteristic
features of the development of the ovum, shortly becomes less
evident, for communication is set up between the mother and the ovum
as soon as it reaches the uterus. Unless we were warned, we might
easily misinterpret the significance of this attachment to the
parent. It does not permit the mother, for instance, to influence the
mind or character which the child will have. The purpose of the
attachment is twofold, namely, to anchor the ovum, and to arrange
channels by which, on the one hand, nutriment may reach the embryo,
and, on the other, its waste products may return to the mother. The
mother may influence the nutrition of the fetus; but she cannot
determine the kind of brain or liver her child will have; neither for
that matter can she alter the development of any portion of the
embryo.