336 A. Aw. W. HUBRECHT. 
in very many instances, but it is in so far instructive, as it has 
a distant analogy to what takes place in the human subject, 
where the decidua reflexa, as it becomes membranous, is 
known to fuse with the decidua vera opposite. The chief 
difference in this case is that there is no decidua vera, but that 
the decidual neoformation is limited to the spherical knob; 
which was fully described above. In the stages of figs. 30 and 
31, during the passive stretching process that was referred to 
above, the crescentic shape which the uterine lumen assumes, 
in consequence of the appearance of the spherical decidual 
proliferation, becomes more and more accentuated. The points 
of the crescent are in this stage continued into the correspond- 
ing uterine glands, which here are submitted to very different 
forces of traction and distension than are in operation either in 
the decidual region or in the surface contiguous to the mesome- 
trium which we have just considered. Figs. 1—-3, on Pl. XV, 
give yet a more adequate idea of the phenomena I have here 
in view. As the distension of the uterus increases with ad- 
vancing pregnancy, these regions are also reached by the pro- 
liferating process described above, and in consequence of the 
combined processes of distension and proliferation these points 
of the crescent! gradually become the direct continuation of the 
lumen. The lumen thus finally surrounds the hemispherical 
protrusion, of which trophosphere and decidua reflexa are the 
constituent elements (figs. 32—34.), and the formation of a new 
epithelium with folds is seen to travel upwards towards the 
region where the placenta will be formed. This extension 
upwards of a renovated epithelium does not affect the surface 
formed by the reflexa, but the opposite surface. In the later 
stages, of which figs. 35 and 36 are the representatives, the 
phenomenon of proliferation becomes more and more accen- 
tuated, the points of the crescent penetrating further and 
further into the fibrillar decidual layer, and tending towards 
each other in the direction that is diametrically opposite to the 
mesometrium. This proliferation thus actively co-operates 
1 It is of course a crescent only in sections; in reality it is a cup-shaped 
space, 
