THE PLASMODI-TROPHOBLAST 
17 
the chromatin network, which in the nuclei of the cyto-trophoblast is more 
open, loose, and reticular. 
The central strands of plasmodium are arranged round the cyto- 
trophoblast in many places as an apparently laminated formation, with 
numerous spaces or clefts, which give an appearance of sharp separation of 
the layers, but between the spaces the cellular layer passes directly into the 
plasmodial. In some of the isolated masses of plasmodium vacuoles occur, 
which are either empty or partially filled with granular material. The 
vacuoles occur in some instances as single spaces, but more frequently they 
are multiple, and all intermediate stages are seen between masses in which 
vacuolation is commencing, and the spun-out plasmoclial reticulum, the meshes 
of which are filled with maternal blood corpuscles. Plate v, Fig. 5, shows 
the characters of the plasmodium as revealed by a higher power of the 
microscope. To the left and below, a mass of plasmodium is seen lying free 
in the blood space, and in the early stage of vacuolation, while further to 
the right, interposed between two portions of decidua, is a larger and more 
vacuolated portion which is in direct contact with the necrotic zone of the 
decidua. It lies in the lumen of a greatly dilated capillary which has 
become directly continuous with the blood space round the ovum by the 
destruction of its wall. The endothelium of the vessel still persists on 
the surface of the detached mass of decidua to the left. At first sight it 
might be inferred that this mass of plasmodium was a portion of the 
closely adjoining network of the same tissue, but this is not so. When 
traced through the series of sections it was found to occupy the lumen of 
the vessel for a considerable distance, and to spring ultimately from the 
general plasmodial mass much nearer the pole of the blastocyst, where it 
could be seen entering a gap in the vessel wall. 
In Plate viii, Fig. 10, an irregular mass of vacuolated plasmodium is 
seen lying in a bay in the necrotic zone; it is extending into the decidua 
in close relation to a vessel which appears in the adjoining sections. 
In other situations large masses of plasmodium are spread out against the 
inner face of the necrotic zone—as if anchoring the ovum in the cavity. 
The great inequality between the plasmodial mass in the upper part 
and that in the lower part of the section figured in Plate ill, Fig. 3, is 
c 
