It would seem, on the whole, that while the influence of maternal impressions in producing definite effects on the child within the womb has by no means been positively demonstrated, we are not entitled to reject it with any positive assurance. Even if we accept it, however, it must remain, for the present, an inexplicable fact; the _modus operandi_ we can scarcely even guess at. General influences from the mother on the child we can easily conceive of as conveyed by the mother's blood; we can even suppose that the modified blood might act specifically on one particular kind of tissue. We can, again, as suggested by Féré, very well believe that the maternal emotions act upon the womb and produce various kinds and degrees of pressure on the child within, so that the apparently active movements of the foetus may be really consecutive on unconscious maternal excitations.[197] We may also believe that, as suggested by John Thomson, there are slight incoördinations _in utero_, a kind of developmental neurosis, produced by some slight lack of harmony of whatever origin, and leading to the production of malformations.[198] We know, finally, that, as Féré and others have repeatedly demonstrated during recent years by experiments on chickens, etc., very subtle agents, even odors, may profoundly affect embryonic development and produce deformity. But how the mother's psychic disposition can, apart from heredity, affect specifically the physical conformation or even the psychic disposition of the child within her womb must remain for the present an insoluble mystery, even if we feel disposed to conclude that in some cases such action seems to be indicated. In comprehending such a connection, however at present undemonstrated, it may well be borne in mind that the relationship of the mother to the child within her womb is of a uniquely intimate character. It is of interest in this connection to quote some remarks by an able psychologist, Dr. Henry Rutgers Marshall; the remarks are not less interesting for being brought forward without any connection with the question of maternal impressions: "It is true that, so far as we know, the nervous system of the embryo never has a direct connection with the nervous system of the mother: nevertheless, as there is a reciprocity of reaction between the physical body of the mother and its embryonic parasite, the relation of the embryonic nervous system to the nervous system of the mother is not very far removed from the relation of the pre-eminent part of the nervous system of a man to some minor nervous system within his body which is to a marked extent dissociated from the whole neural mass.