(1) The imagination-theory, or, to quote Harvey: "Due to mental causes so operating either on the mind of the female and so acting on her reproductive powers, or on the mind of the male parent, and so influencing the qualities of his semen, as to modify the nutrition and development of the offspring." (2) Due to a local influence on the reproductive organs of the mother. (3) Due to a general influence through the fetus on the mother. Antenatal Pathology.--We have next to deal with the diseases, accidents, and operations that affect the pregnant uterus and its contents; these are rich in anomalies and facts of curious interest, and have been recognized from the earliest times. In the various works usually grouped together under the general designation of "Hippocratic" are to be found the earliest opinions upon the subject of antenatal pathology which the medical literature of Greece has handed down to modern times. That there were medical writers before the time of Hippocrates cannot be doubted, and that the works ascribed to the "Father of Medicine" were immediately followed by those of other physicians, is likewise not to be questioned; but whilst nearly all the writings prior to and after Hippocrates have been long lost to the world, most of those that were written by the Coan physician and his followers have been almost miraculously preserved. As Littre puts it, "Les ecrits hippocratiques demeurent isoles au milieu des debris de l'antique litterature medicale."--(Ballantyne.)