B. MONSTROSITIES PRODUCED HY EXCESS OF DEYELOPEMENT.
I. Foetus in Kent.
The human foetus may be included in an other fretus, or adhere to its body. This may happen in two different manners : A flans more or less perfect contained in the cavity of the body if its twin-brother or sister.
a. In the uterus. The foetus would be pregnant in such a case at the moment of its birth. The observations given of it are, however, somewhat apocryphal.
b. In the abdomen. In acase recorded by Fattow, there are, in a foetus of seven months, two rudiments of feetuses contained in its abdomen. Such observations are also given by Reiter, Herninger, Pacini, and E. Philips. In general, the rudiments of a second foetus are very imperfect, and included in a sac. Sometimes, however, they are more complete, which was, for example, the case in an observ ation of of which the preparation is preserved in the splendid Museum of the Limclon College of Surgeons.
c. In the anterior mediastinum. As in a case recorded by Gordon, in a female of twenty one years.
d. In the scrotum and the testes. Such cases have been noticed by Rosenberger, Hartmann, D. S. J. Wendt, Velpeau. Some times the rudiments of a second fcetus are found in the interior of the testis, sometimes at its exterior surface.
e. In the stomach.
f. In the intestinal canal. Highmore has given such a case in a youth of fifteen or six teen years, in the gut of whom an acephalus was found.
g. In the orbit. According to Barnes.
h. At the tentorium of the dura matey.
i. At the palate. It is then in the form of a fungous excrescence, consisting of the rudiments of a second foetus (Otto, Sandi fort, Ehrman, Stailenski).
2. The more or less developed rudiments of a ftetzis adhere, in the form of a tumour, to the external surface of a second body, and ate covered by the external integu ments.
a. To the cheek. G. Vrolik observed in a new-born male child, a sac of large circum ference, covered by the external skin, and ad hering to the region of the left check, but without communication with the mouth. In this sac there were tuberculous cartilages, os-i seous nuclei, and organised parts of indefinite form and composition.
b. To the neck. to Joube.
c. To the epigastric and umbilical region.
As recorded by E. B. Gaither.
d. To the sacral and perineal region. This is the most frequent mode of adhesion, as is proved by a great many observations, among which those of Himly and of Fleischmann deserve special mention. This adhesion takes place in different manners : 1. by external cellular tissue; 2. by internal union with the abdominal and pelvic cavity (Himly, Schau mann, and Stanley) 3. by communication with the spinal canal. There is sometimes no vascular communication between the fcetus and its appendix (W. Vrolik) ; and in other cases there are large branches going from the arteria sacra media of the fletus to the sac. In general, the sac has its own integuments, over which passes the skin of the fcetus. The genital parts and the anus are always quite separate from the sac, which merely lies in apposition with them. In the majority of the known cases,. the rudiments of a fetus contained in the sac are but confused and ill-determined organic substances, intermin gled with a few osseous and cartilaginous nuclei. In one case it was possible to recog nise the cranium with the face and the naked encephalous masses (Wedemeyer) ; Mayer and Blizard found an intestinal loop; Himly saw distinct super-maxillary bones, and ru diments of temporal, frontal, and sphenoid bones, &c.
If we take a survey of all the cases which are designated as fcetus in ftetu, it is clear that some may be compared with parasitical dis eases formed in the interior of the body of the fetus. I presume that this is the case, when the mass which is found consists only of hair, fat, teeth, and some osseous nuclei, contained in a cystic tumour. In other cases the rudiments of a fcetus are included with a more or less perfect indication of an ovum in the body of a second fcetus, or adhere exter nally to it. The large number of theories on the origin of this monstrosity have been criti cised by Himly. It is certain that none of them can be maintained. It is most pro bable that the fetus in fcetu is an incomplete effort to form a double monster. In this sense, some cases of fcetus in fictu make a transition towards that form of double mon sters which is named hetcradelph.