IMBEDDING OF THE OVUM 
43 
case of the embolus, the necrosis is at first progressive, but soon, reaction 
taking place in the surrounding tissue, it becomes more capable of resistance, 
and consequently of effecting a union with the trophoblastic processes, as 
will be described later. 
The appearances of the necrotic zone of the decidua and of the 
plasmodium in our ovum all suggest that the process of destruction is 
not one of erosion by direct cellular activity or phagocytosis, but a sort 
of digestion or solution due to the action of extra-cellular substances pro¬ 
bably of the nature of enzymes. Further, it appears probable that the 
vacuolated and spun-out condition of the plasmodium is due to the forma¬ 
tion in the vacuoles of a digestive fluid, and that when this is shed by the 
rupture of the vacuoles its place is taken by maternal blood. In this way 
all the appearances of the plasmodium are readily explained. Possibly the 
secretion also contains an enzyme which prevents coagulation of the blood ; 
but it is also not impossible that the surface of the plasmodium may behave 
towards the blood like an endothelium, thus preventing coagulation. The 
fact that coagulation readily occurs in the neighbourhood of the placenta, or 
tumour, when a considerable extravasation has taken place, is rather against 
the idea that there is an active coagulation-hindering enzyme. 
The plasmodial formation characteristic of the present ovum has 
hitherto been described only in connection with a young ovum recorded 
by Stolper. The ovum which measured 2’5 x 2*2 mm. in diameter, was 
obtained by curetting undertaken on account of menorrhagia simulating 
abortion, although no menstrual period had been omitted. It presented 
a close resemblance to Peters’ ovum, and was fairly well fixed. On 
one side of the ovum the villi were long and rather more advanced in 
appearance than in Peters’ case, but on the other side there was an 
extraordinary development of spun-out plasmodium, which was not attached 
to the adjacent decidua, and was not accompanied by a corresponding 
development of the Langhans’ layer. Much of this plasmodium was 
degenerated or even necrotic, and Stolper states that “ es kann nicht 
physiologisch sein.” In the light of our ovum, the occurrence of such a 
condition of the plasmodium in Stolper’s case, probably represents the 
abnormal persistence of what is normal in an earlier stage. 
