With the possible exception of such individuals as are spending their lives in solitary confinement, there is scarcely a human being who has not in the course of nine consecutive months some untoward physical or mental experience which engraves itself upon the memory. Prospective mothers are not apt to be exempt from a rule so general in its application, but if by good chance one happens so to be she will hardly fail to hear of the misfortune of others, which, according to the doctrine of maternal impressions, may be equally effective in interfering with the proper development of the child. We should then rightly expect most, if not all, babies to be "marked"-- clearly a situation which does not prevail. In order to learn how frequently prospective mothers may have disagreeable experiences which they fear will affect the formation of the child, I have lately asked the patients whom I have attended, "Was there any incident during your pregnancy to which you could have attributed the infant's condition, had it been marked?" The babies of all those to whom the question was submitted were normal; yet without exception those whose pregnancies just completed were their first answered in the affirmative. It is also pertinent that one of these patients had lost her brother by a violent and accidental death when she was four months pregnant; a similar bereavement was suffered by another at the eighth month; each was, however, delivered of a perfectly healthy child. Among those with whom the recently ended pregnancy was not the first I found some who could remember incidents popularly believed to have an influence over the development of the embryo; most of them, however, had given the matter so little thought that they could not definitely recall whether such incidents had occurred or not. From a similar series of observations covering two thousand cases, William Hunter came to the conclusion, nearly two hundred years ago, that there was no support for the belief in maternal impressions. Whenever a child does happen to develop abnormally, it must be clear that, from the very nature of our existence, some incident can be recalled which will satisfactorily, yet unjustly, bear the blame. It may be confidently said, however, that, for every mother whose fears are realized, hundreds are agreeably disappointed in finding their babies perfectly normal. In the face of so many negative instances it is amazing that any person, even though ignorant of medical teaching, should be inclined to attribute abnormal development to something the mother has seen or heard, thought or dreamt, or otherwise experienced while she was pregnant. Yet unfortunately many do believe this. It is worth while, therefore, to supply further evidence, and thus escape any suspicion of unfairness in argument, to prove that maternal impressions are unable to affect the formation of the embryo.