408 MINOT. [Vot. II. 
is often corrugated, and then the line of separation between the 
tissues is irregular, and in sections it may even appear that 
there is a true interpenetration and mingling of the decidual and 
ectodermal cells; but it is only apparent, and the demarcation is 
always preserved. 
At the edge of the placenta, as shown by examination of after- 
births, the relations of the layers are somewhat different. I 
reproduce with a few additions the descriptions given in my 
article on the Placenta’ of a radial section through the 
margin of a normal placenta discharged at full term, Cut 24, 
A, from which the amnion had been removed. The chorion, 
Cho, and decidua, D, are in immediate contact at the left of 
Cut 25. — After-birth at full term; vertical section of the amnion, chorion, and 
decidua in their natural relations near the placenta. am, amnion; cho, chorion; 
¢, cellular layer or ectoderm; 7, fibrine and decidual tissue, degenerated; D’, decid- 
ual tissue. XX 125 diams. 
the figure; that is, outside of the placenta, though remnants of 
the aborted villi, vz, are still plainly recognizable; but, as stated 
previously, they occur only in the immediate neighborhood of 
the placenta. These villi are surrounded by hyaline matter which 
resembles and can be followed into continuity with the canalized 
fibrine layer, /26, covering the surface of the decidua serotina 
and the fibrine layer of the chorion frondosum. Below the 
aborted villi, vz, of the chorion lave, the fibrine layer is broken 
down and penetrated by the decidual tissue, so that the demar- 
1 Wood’s Reference Handbook Medical Science, V., 694, 695. 
