The evolution of man : a popular exposition of the principal points of human ontogeny and phylogeny . Fig. 200.—Human embryo, twelve weeks old, with its coverings; naturalsize. The navel cord passes from the navel to the placenta : b, amnion;c, chorion ; d, placenta ; d\ remains of tufts on the smooth chorion ; /, de-cidua refiexa (inner) ; g, decidua vera (outer). (After Bernhard Schultze.) latter is not attached to the placenta. The placental orspongy deciduous membrane (d. placentalis or serotina,Fig. 198, pin, Fig. 200, d) is simply the maternal placenta THE DECIDUOUS MEMBRANE IN MAN AND A
The evolution of man : a popular exposition of the principal points of human ontogeny and phylogeny . Fig. 200.—Human embryo, twelve weeks old, with its coverings; naturalsize. The navel cord passes from the navel to the placenta : b, amnion;c, chorion ; d, placenta ; d\ remains of tufts on the smooth chorion ; /, de-cidua refiexa (inner) ; g, decidua vera (outer). (After Bernhard Schultze.) latter is not attached to the placenta. The placental orspongy deciduous membrane (d. placentalis or serotina,Fig. 198, pin, Fig. 200, d) is simply the maternal placenta THE DECIDUOUS MEMBRANE IN MAN AND APES. 167 itself, or the maternal part of the vascular cake (pla-centa uterina), , that part of the uterine mucous mem-brane which coalesces intimately with the chorion-tufts of. Fig. 201.—Mature human embryo (at the end of pregnancy), in its naturalposition, taken out of the uterus. On the inner surface of the latter (onthe left) is tbe placenta, which is attached to the navel of the child by thenavel cord. (After Bernbavd Schultze.) the embryonic placenta (placenta fcetalis). Lastly, theinner or false deciduous membrane (d. interna or reflexa,Fig. 198, dr, Fig. 200, /) is that portion of the uterine mucousmembrane which, as a peculiar thin envelope, covers all therest of the egg-surface, lying immediately over the tuftlesssmooth chorion (chorion Iceve). The origin of these threedistinct deciduous membranes, concerning which erroneousnotions have been entertained (still retained in the nomen-clature), is plain enough; the external or true deciduous l68 THE EVOLUTION OF MAN. membrane is a peculiar modification, afterwards lost, of thesuperficial layer of the original mucous membrane of theuterus. The placental membrane is that portion of thepreceding which i
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