394 A. A. W. HUBRECHT. 
Fig. 2 is taken through the centre of a decidual swelling at a very early 
stage, the embryo (e.) being still free in the recess of the uterus lumen. 
This lumen has here been considerably encroached upon by the symme- 
trical proliferation in the antimesometrical portion of the mucosa. 
The tubular glands are fast undergoing a retrogressive metamorphosis 
in the region of this proliferation, their blind and coiled ends not 
being affected in the same way. ‘The proliferating decidual tissue is 
very compact. Besides the cellular stroma, strands of vasifactive 
tissue may be distinguished in it; but as yet hardly any lumina of 
blood-spaces are visible (cf. Fig. 37). At the lips of the swelling 
there is a hemorrhagic edema. The blood-extravasate, by which the 
mouth of the recess is going to be closed, is represented in this figure 
as situated in the uterus lumen. 
Fig. 3 is a later stage than the foregoing. The decidual swelling has 
become highly vascular, the lips of the recess have coalesced, and the 
embryo is shut off from the uterine lumen by a true decidua reflexa. 
The embryo is further developed (cf. Figs. 19 and 20), the germinal 
area established, the trophoblast (Z7.) fused with the maternal tissue, a 
special trophosphere (7'S.) forming the central nucleus of the vascular 
decidual swelling. 
Fic. 4.—A very early embryo, drawn with the camera. Actual size 
ce? th mm. Ay. Hypoblast. Zr. Trophoblast. (Mus. Utr. Cat. no Erin. 
137 are les.) 
Fic. 5.—The same embryo (Z.) a few sections further, represented in situ 
at the bottom of the decidual depression (cf. Fig. 2). e. The epithelium of 
this depression. g/. The glands in retrogressive metamorphosis. D. The 
stroma of the decidual proliferation. For better histological detail of this 
stage see Fig. 37. (Mus. Utr. Cat. n® Erin. 137 @, 37. 3s.) 
Fie. 6.—Another embryo a little further advanced, taken from the same 
mother. (Mus. Utr. Cat. no Erin. 137 67, 37. 3s.) 
Fic. 7.—A somewhat older embryo, more considerably enlarged and drawn 
with the camera. The embryo is no longer in the lumen of the recess, 
but is enclosed by the decidual stroma after partial disappearance of the 
uterine epithelium (¢.). The lumen of the recess is in this stage already filled 
by a coagulum (coa.) (cf. Figs.2, 3, and 39). Ay. The hypoblastic vesicle. 
1 The relative size of the embryo in this figure is much too large. 
2 The n° and letters following upon the abbreviation for Hrinaceus are 
the reference numbers for the Catalogue. Then follow letters 7 and s, pre- 
ceded by a numeral. These stand for vow and section, so that, e.g. the 
original of fig. 6 is found by examining the third section in the third row of 
the series that is catalogued under the n®” Erinaceus, 137 27. 
