(2) The influence of the acquired personal characteristics of the parents (particularly the acquired characteristics which are especially active at and just previous to the time of actual conception), transmitted to the child along the lines of heredity. (3) The influence of "maternal impressions" (after conception, and during the period of gestation or pregnancy) transmitted to the child physiologically and psychologically. I shall now ask you to proceed with me to a consideration of the various phases of Pre-Natal Influences coming under the above name three general classes, and the principal factors involved therein. Heredity in General. By "heredity" is meant "the tendency which there is in each animal or plant, in all essential characters, to resemble its parents"; or "the hereditary transmission of physical or psychical characteristics of parents to their offspring." There is a great disagreement among the authorities as to how far the principle of heredity really extends, and the real causes of heredity are in dispute. In the present consideration we shall, of course, pass over the technical phases of the subject, and shall touch only upon the general features and principles involved. Shute, in his work entitled "Organic Evolution," says: "That an offspring always inherits from its parents many of their characteristics is well known; that it always varies, more or less, from them, is also equally well known. Heredity and variation are twin forces that play upon every creature, holding it rigidly true to the parental type or compelling more or less divergence therefrom, according to the strength of the one or other power; so that every creature is the resultant of the activities of these two great parallel forces. Variation is co-extensive with heredity, and every living creature gives evidence of the existence of variations. "Mental heredity can be illustrated by studying the genealogies of such persons as Aristotle, Goethe, Darwin, Coleridge, Milton, etc. Probably the Bach family, of Germany, supply one of the best illustrations of the inheritance of intellectual character that we know of. The record of this family begins in 1550, lasting through eight generations to 1800. For about two centuries it gave to the world musicians and singers of high rank. The founder was Weit Bach, a baker of Presburg, who sought recreation from his routine work in song and music. For nearly two hundred years his descendants, who were very numerous in Franconia, Thuringia, and Saxony, retained a musical talent, being all church singers and organists. When the members of the family had become very numerous and widely separated from one another, they decided to meet at a stated place once a year. Often more than a hundred persons--men, women, and children--bearing the name of Bach were thus brought together. This family reunion continued until nearly the middle of the eighteenth century. In this family of musicians, twenty-nine became eminent.