=All That a Child Possesses at Birth Not Necessarily Hereditary.--=We come now to the more specific discussion of what may happen to offspring of mammals, and particularly man, in the interval between fertilization and birth; that is, during the intra-maternal period. We have already seen that anything affecting the offspring during this period has to be reckoned as environmental, our formula reading, Mammal = germ + intra-maternal environment + external environment. It is evident, then, that all that a child possesses at birth is not necessarily hereditary, since the unborn child may be influenced by conditions prevailing in either parent. =The Myth of Maternal Impressions.--=In order to clear the way for more urgent matters let us first inquire into the question of the production of changes in the unborn child as a result of "maternal impressions." As the tale generally goes, structural changes are produced in the unborn child corresponding to some mental experience of the mother, usually a vivid impression of strong emotion, but when a given individual is pinned down to sources, it is usually a case of hearsay. Stock examples are: The mother sees a mouse with the result that a mouse-shaped birthmark occurs on the child; or she sees a crushed hand and in consequence bears a child later with some of the bones of the hand missing; the mother touches her body when frightened and thus marks the unborn child on the corresponding part of the body; or she produces beauty in the child by long contemplation of a picture of a beautiful child; and so on almost endlessly. The favorite is usually the production of a red birthmark or marks on the child's body by strong desire on the part of the mother for strawberries, tomatoes, etc.--the fruit must be red since the mark is red--or by fright from seeing a fire. As a matter of fact it is not uncommon for the capillary blood vessels of the skin of a new-born infant to remain dilated in spots instead of contracting as they normally should do. The result is more or less of a red or "flame" spot. It is easy to see, therefore, why such birthmarks are so frequently referred back by the credulous mother to her desire for or fear of some red object.