In this division we include malformations in which there is little or no quantitative defect, but there is a qualitative difference from the normal, an error in the development; they are the forms which Foerster has classified as Monstra per fabricam alienam. The malformations affect the thoracic and abdominal viscera and the external organs which are in immediate connection with them. The heart and blood-vessels and the generative organs are most frequently affected. The malformations of these will be described in their special section; we have here to deal with general monstrosities.

Transposition Of The Viscera (Situs Transversus)

This malformation is not very rare. The entire viscera of chest and abdomen are transposed, so that the aorta comes off from a right ventricle, the venae cavse are on the left side, the liver is on the left, the spleen on the right, and so on. The organs are properly formed, and their function is normal. The existence of the malformation may altogether escape observation, or may be accidentally discovered when the person is being examined medically.

Transposition is constant in double monsters, the left twin having the normal arrangement, and the right having the viscera transposed. This seems to indicate that in single embryoes the usual situation in the umbilical vesicle is left, but that occasionally it may be right, in which case the viscera are transposed.

Literature

Meckel, Handb. d. path, anat., 1812-1818; and De duplicate mon-strosa comment., 1813; Etienne Geoffroy St. Hilaire, Philosophic anatomique, vol. ii., 1822; Isidore Geoffroy St. Hilaire, Traite de teratologic, 1832-1837; Vrolik, Tabulae, 1849. The fullest account in Foerster, Die Missbildungen des Menschen, with atlas, 1861, and in Ahlfeld, Die Missbildungen des Menschen, 1880-1882, also with atlas; in both of these the literature very fully; also Gerlach, Die Entstehungsweise der Doppelmissbildungen, 1882; Panum, Die Entstehung der Missbildungen, 1860; Dareste, Kecherches sur la production artificielle des monstrosity, 2nd ed., 1891; Hirst and Piersol, Human monstrosities (causation, classification, and literature somewhat fully), 1892; Raurer, various papers on the theory of monstrosity by excess, in Virchow's Arch. vols, lxxi., lxxii., lxxiii., lxxiv. Cleland, Journal of Anat. and Phys., vols, viii., xii., xiii., xvii. Trans, of Philosoph. Soc. of Glasgow, 1885-86. Address on Rational Teratology, Brit. Med. Jour., 1888, vol. ii., p. 346, also Memoirs and Memoranda in Anatomy by Cleland. Mackay, and Young, 1888. Himly, Foetus in foetu, 1831; Sneddon (Supernumerary mamma), Glasg. Med. Jour., pp. 69 and 120, 1878. Bannatyne, Diseases and Deformities of foetus 1894-95 and Teratologia, a journal, vol. i., 1894. Teacher and Coats (Siren), Jour, of Path., 1895.