without abortion taking place. It is naturally expected that, as has been shown to be the case in placenta prævia and in the separation of decidua in extra-uterine pregnancy, the detachment of bits should take place near the internal os, where it would least disturb the ovum. These are cases of threatened abortion, and among them may be included cases of extreme rarity, of abortion of one of twins, while the other remains in utero, and goes on in its development.
This abortion of one of twins may be a missed abortion: or the miscarriage of one of twins may be a missed miscarriage. In that case the fœtus and its envelopes, instead of getting rolled up into a parcel-like form, as I shall describe to you, become compressed and squeezed flat between the uterus and the growing ovum into the condition which, when extreme, is called fœtus papyraceus. I show here a beautiful specimen of fœtus papyraceus, occurring in a case of twins where there was missed miscarriage.
To recapitulate: In cases of threatened abortion you may have a discharge of a bit of decidua; you may have the neck of the womb open to the extent of allowing the finger to pass, and to feel the ovum: and you may have a missed abortion or a missed miscarriage in the case of twins.
Missed abortion is neither a threatened abortion or miscarriage, nor an imperfect miscarriage. In order that you may understand an imperfect miscarriage (of which I have a remarkable instance to describe to you), I must tell you what is a complete or perfect miscarriage. If the fœtus alone, or the entire ovum alone, comes away, the woman has miscarried, or aborted, as it may be; but the coming away of the ovum does not involve a complete miscarriage; and an imperfect miscarriage is often a very disastrous thing. The ovum sometimes comes away alone, without any of its uterine
