ATTACHMENT OF THE OVUM 45 
The further changes could be conceived as follows: the greater part 
of the early plasmodium disappears after being spun out into the fine 
threads seen in many parts of our sections, while the marginal cells of the 
cyto-trophoblastic columns continue to form new plasmodium. On the 
other hand, the plasmodium may in part persist, the strands arranging 
themselves over the cytoblast columns as an endothelium-like layer, while 
Figure VIII. Diagram of a Hypothetical Stage of the Human Ovum imbedded 
in the Decidua somewhat younger than Peters’ Ovum. The Embryonic Rudiment 
is proportionally on too large a scale. (T. H. Bryce, from “Quain’s Anatomy,” 
11th Ed. Vol. I.) 
the outlying parts remain as the irregular masses invading the decidua. 
It appears probable that the extensive plasmodium is in great part a 
temporary formation provided for the early enlargement of the implan¬ 
tation cavity. The attachment of the ovum is effected when the columns 
of cyto-trophoblast reach the decidua at points from which the necrotic 
layer has been removed, and become fixed by the terminal cells insinuating 
themselves among the elements of the decidua. The accompanying figure 
(Figure vm) presents in a diagrammatic form an ovum at a stage inter¬ 
mediate between our ovum and that of Peters. 
J 
