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undergoing hyaline degeneration, that at three months the degenera- 
tion is considerably more advanced and that by the sixth and seventh 
month the reflexa can no longer be found. These observations justify 
the theory that the reflexa degenerates and is completely resorbed. 
I will review briefly the actual observations. 
First the reflexa at two months. — It starts from the edge of 
the placental area with considerable thickness, which is rapidly lost» 
most of the reflexa being a thin membrane, and the thinnest point 
being opposite the placenta. The examination of sections shows that 
the entire reflexa is undergoing degeneration, which is found to be 
the more advanced the more remote the part examined is from the- 
placenta. The chorion laeve lies very near the reflexa, being separated 
only by chorionic villi, which are very much altered by degeneration, 
their ectoderm having become a hyaline tissue, which stains darkly 
and their mesoderm showing clearly the partial loss of its cellular 
organization. In the region half way between the base and the apex 
of the reflexa dome the tissue of the decidual membrane shows only, 
vague traces of its original structure; only here and there can a di- 
stinct cell with its nucleus be made out, for most of the cells have 
broken down and fused into irregular masses without recognizable 
organization. Ramifying through the fused detritus there are two 
layers of so-called „fibrine“ — or in other words of a hyaline sub- 
stance, which like the ,,canalized fibrine“ of the chorion stains very 
deeply with the ordinary histological dyes, — carmine and logwood. 
The fibrine is much more developed upon the outer side of the re- 
flexa. It forms on the inner side a dense network, which on the 
one hand fuses with the degenerated ectoderm of the chorionic villi 
whereever the villi are in contact with the decidua; — and on the 
other hand ramifies more than half way through the decidua, the 
ramifications being easily followed owing to the hyaline character and 
deep staining of the „fibrine“. Upon the outside the fibrine forms a 
thinner layer and shows its network structure in many sections much 
less clearly. 
All of these points are illustrated in the accompanying figure, 
the outlines of which were made with the camera lucida, the details 
added free hand. A chorionic villus is seen in cross sections, 
and is bounded by its own degenerated ectoderm; the inner fibrine 
layer forms a distinct network and extends far into the decidual 
tissue, which is so disorganized that only vague traces of cells can 
be distinguished; the middle layer of the decidua contains almost no 
fibrine; the outer layer is well marked, compact and narrow. 
