... Changes in mode of life and in intellectual occupation are so frequent among all classes that materials must exist for determining whether such changes during the prenatal period have any influence on the character of the offspring. The present communication may perhaps induce ladies who have undergone such changes, and who have large families, to state whether they can trace any corresponding effect on the character of their children.--_Nature_, August 24 1893, pp. 389, 390. Yet this suggestive pronouncement of the world-famous naturalist has never been seriously followed up by scientists. I think the time is now ripe for a definite statement that: _The view that the pregnant woman can and does influence the mental states of the future child is to-day a scientific hypothesis which may be shortly proved_. I make this definite statement, in conjunction with the cognate and illuminating facts from other fields of research, a few of which are discussed in the following pages. That our mental states can affect, not only our spirits and our points of view, but actually the physical structure of our bodies, is demonstrable in a hundred different ways, and appears either to be proved or merely suggested according to the bias and temperament of the one to whom the demonstration is made. But there is one at least of these physical correlations which can be demonstrated with scientific thoroughness, and which proves beyond doubt that the mental state of the mother _has_ a reaction upon her infant even after it has severed its physical connection with her, and is a baby of a few months old. This fact is that a nursing mother who is subjected to a violent shock which results in a paroxysm of temper or of terror in her own mind, conveys the physical result of this to her infant when next she nurses it, so that the child has either an attack of indigestion or a fit. The effect of the mother’s mental state is transmitted by the influence on the milk, the chemical composition of which is subtly altered by her nervous paroxysm, and which thus acts as a poison to the infant. A much more subtle and closer correlation must exist between the mother’s mental states and the child when it is still not yet free and independent in the outer environment of the world but while it finds in her body its entire environment, its protection and the resources out of which it is building its own structure, while the blood and the tissues of her body form its whole world, while through them and through them alone can it obtain all its nourishment.