II. Deformation of the originally well farmed germ.— 1. It is said that this may be produced by mental impression of the pregnant woman, or what the German authors call das Versehen. But for this opinion no positive proof can be afforded. According to the observations pub lished thereupon, and of which a great deal may be found in the learned article GENERATIoN of this Cyclopedia, all the supposed mental impressions, which have been considered as the cause of malformations, took place, with few exceptions, in the last stage of preg nancy.# And even in those casesin which an earlier period may be certified, we could object that the post hoc must not always lead to the conclusion ergo propter hoc. It is of some im portance to appreciate the correctness of this reasoning, for the theory of the mental im pressions, which was so readily adopted in the barbarous middle ages, as a mode of saving poor and innocent women from torture and stake, finds even in the present day more ad vocates than might have been expected. Of this I was convinced at the Congress of Naturalists at Aix-la-Chlwelle in 1847, and in the Report of the Transactions of the Sch wei zerischen Eiday: Gesellschqft zu Char, 29, 30, 31 Juli, 1844, in which the aflected mind of the pregnant woman is said to produce a mysterious effect on the foetus, and that the medium by which this influence is com municated may be the hearing as well as the sight ! To crown all these absurdities, we see mentioned in Rust, Magasin, B. xxi. S. 261., that a woman gave birth to a child with im perfect bones, which is attributed to her having been present, before her pregnancy, at the execution of a criminal by breaking on the wheel. To all these fantastical considera tions I oppose the following arguments : a. That malformations seldom, or perhaps never, agree with apprehensions or fears d priori of pregnant women (G. Vrolik, T. Zimmer, J. J. Plenck, and Burdach). On the contrary, it often happens that a woman who has once procreated a malformation, and is continually troubled by the fear of another -similar sad occurrence, may become the happy mother of a second well-formed child.
b. That the foetus, even when a germ, is quite independent ; transferred from the ovary into the uterus, it needs for its development a material intercourse with the maternal body, but no organic connection ; for which reason it'can be formed as well without as within the uterus, as in extra-uterine pregnancy ; that it stands in no connection, either vascular or -nervous, with the body of the mother, and that therefore it is improbable that her mental .condition can have any influence whatever upon the form of the foetus.
c. That malformations occur likewise among the inferior animals,—insects, testaceous ani mals, echinodermata,—in which the develope ment of psychical life is very imperfect, and the oviparous generation of which must pre serve the young from the influence of dis ordered maternal imagination.
d. That in the case of twins, as the ace phali specially show, one child may be mal formed and the other in perfect condition, notwithstanding they were both exposed to the same influences.
c. That more deeply situated organs, the very existence of which may be unknown to the pregnant woman, may he malformed ; as for instance, the heart, the intestinal tube, &e.
If now, on all these grounds, I exclude the mental impressions of pregnant women from the aetiology of malformations, I do not mean to deny the influence which by her somatic condition the mother may exercise upon the flews. Thus, if in consequence of mental agitation, her body were to suffer a violent shuck, this might have a prejudicial influence on the material transmission which takes place between her and the foetus, and the latter might thereby become morbidly affected. There arc instances of its being the subject of intermittent fever (P. Russell) ; of sudden death occa sioned by frightful agitation of the mother (Wienholdt) ; of jaundice communicated by the mother (Kerckring) • of small-pox (Joi ner, Montgomery, Friedlander) ; of syphilis and scarlet fever (It. Lee), all derived from the mother. But all this is entirely different from the effect of mental impressions. It is a material result, easily conceived, and of which physiologists need no further explanation.
2. A second cause of malformation of the foetus is sought in external injury suffered by women during their pregnancy. Meckel goes so far as to reject this entirely. In sonic de formities, for instance, in hydrops ventriculu rum cerebri, the effect of external injury is easily proved.
3. A third cause is attributed to diseases of the ovum and of the foetus. Simpson (Edinburgh Med. and Surg. Journal, No. 127., April, 1836, and Gazette Medicale de Paris, Nov. 1836, p. 393.) has described an acute and chronic form of placentitis, to which ought to be ascribed all those singular ex udations which attach themselves to the foetus as pseudo-membranes. Fig. 595. gives a :.pe chnen of adhesion of the placenta to the head of a foetus deformed by urania.
In fig. 596. a pseudo-membrane passes to the forehead, round which is twisted the um bilical cord, In some, but very rare, cases, the coats of the ovum are destroyed, and the foetus is im mediately attached to the inner surface of the uterus (Steinmetz). It is not to be denied, that through these pseudo-membranes some mal formations of the foetus may be occasioned, as Montgomery has proved, such as the truncation of the extremities, which he names setf-anzpu lotion. Further than this, however, we may not go, for the brides placentaires of Professor St. Hilaire are certainly not a universal cause of monstrosity. They are too accidental and unstable to be such. The existence of mal formations in eggs which Geoffroy St. Hilaire coated over with varnish or wax, affords no proof of the possibility of a mechanical origin of monstrosities. The exclusion of the air pre vents, in such a case, the necessary material change in the ovum, in consequence of which the perfect developement of the foetus is im paired.