We can artificially obtain double embryos of frogs by inverting the blastomeres in the two-cell stage.[58c] We thus get united twins with heads turned in opposite directions, twins united back to back like the Blazek Sisters, twins united by their ventral sides, and double-headed tadpoles, but we have no knowledge of how similar doubling in human monsters takes place; we must guess vaguely from analogy. There was one soul, at least, present from the one-cell stage of the human monster; when the second soul is created and infused we do not know, but the moment of the creation of this second soul has no practical significance in this discussion.
The presence of certain kinds of monsters in the uterus can be diagnosed before labor, but double monsters are mistaken for ordinary twins. A woman who has given birth to a monster is likely to have subsequent monstrous fetuses. Where the intrauterine existence of a single monster is suspected the X-ray will at times clear up the diagnosis. Women gravid with monsters commonly abort early in pregnancy, but even united twins may go on to term. Those monsters that offer an obstacle to delivery by the abnormal bulk of one or the other end are mostly twins joined above or below the navel; those joined at the middle are easier of delivery. Monsters that are joined at the pelves are commonly in a straight line, and may not be difficult to deliver. Most double monsters cannot be delivered alive except by cesarean section, and the fact that the content of the uterus is monstrous is, as a rule, not diagnosed until it is impossible to attempt cesarean section without killing the mother through infection. In such a condition the double monster would, in the ordinary medical practice, be delivered by craniotomy, exenteration, cleidotomy, or the like operation.
The _Rituale Romanum Pauli V_[59] gives the following directions for the baptizing of human terata:
"18. In monstris vero baptizandis, si casus eveniat, magna cautio, adhibenda est, de quo si opus fuerit, ordinarius loci, vel alii periti consulantur, nisi mortis periculum immineat.
"19. Monstrum, quod humanam speciem non praeseferat baptizari non debet; de quo si dubium fuerit, baptizatur sub hac conditione; _Si tu es homo ego te baptizo_, etc.