THE DECIDUOUS MEMBRANE IN MAN AND APES. 1 67 



itself, or the maternal part of the " vascular cake " (pla- 

 centa uterina), i.e., 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 natural 

 position, taken out of the uterus. On the inner surface of the latter (on 

 the left) is the placenta, which is attached to the navel of the child by the 

 navel cord. (After Bernhard Schultze.) 



the embryonic placenta (placenta fcetalis). Lastly, the 

 inner or false deciduous membrane (d. interna or rejiexa, 

 Fig. 198, dr, Fig. 200, /) is that portion of the uterine mucous 

 membrane which, as a peculiar thin envelope, covers all the 

 rest of the egg-surface, lying immediately over the tuftless 

 smooth chorion (chorion Iceve). The origin of these three 

 distinct deciduous membranes, concerning which erroneous 

 notions have been entertained (still retained in the nomen- 

 clature), is plain enough ; the external or true deciduous 



