318 A. A. W. HUBRECHT. 
der Maus, Pl. 1, fig. 6). Also in other rodents he has noticed 
similar facts, and so material for a more decisive answer i 
accumulating on different sides. When the hedgehog’s blasto- 
eyst has still further become embedded in the subepithelial 
stroma, no further trace of epithelium is detected round it; 
both in fig. 7 and fig. 839 we see that it has, so to say, sunk 
through the bottom of the depression, and that there is no 
trace of the epithelium that covered the spot where it has 
adhered (as we have already seen in fig. 38), but that even in 
these later stages the uterine epithelium is still preserved close 
above the embedded blastocyst (e., e., figs. 7 and 39). 
One other fact would perhaps make the view acceptable that 
there is indeed a direct destructive action exercised by the 
blastocyst leading to the local disappearance of the epithelium. 
This fact is figured Pl. XV, fig. 8 a, and more in detail Pl. XXII, 
fig. 39. The thickest part of the wall of the blastocyst (what 
we have called the polar knob in a preceding chapter) is here 
seen to surround a spherical cellular projection, which in fact 
is nothing else but a remnant of a uterine gland. This is of 
course no direct evidence, but the preparation certainly sug- 
gests the idea that the blastocyst, which appeared to have a 
corroding action on the uterine epithelium (fig. 38), is here 
caught in the act of attacking a fragment of tissue that is a 
direct derivate of that same uterine epithelium, and of which, 
also in later stages, no more traces can be detected in the - 
immediate vicinity of the blastocyst. 
And so the epithelium of the uterus takes no part in the 
attachment of the blastocyst, neither that of the depression J, 
nor that of the glands g/. The different phases which this 
disappearing epithelium further passes through can thus 
hardly interest us. Once the embryo safely lodged in the 
decidual stroma the epithelium is doomed to destruction, and 
we have seen above that the blood-clot there mentioned 
absorbs a great portion of its remains. It may suffice to 
refer to figs. 37, 38, and 39. 
Simultaneously with this embedding process of the blasto- 
cyst important modifications of the surrounding stroma of the 
