352 A. A. W. HUBREOCHT. 
I have now abandoned my original view of the question, and 
that I come to the same conclusions as yourself. The material 
which I have collected this year has allowed me to study a 
developmental stage which I had not yet examined till now. 
The preparations show, with most perfect evidence, that the 
epiblast in the entire area of the future placentary region is 
doubled, at the time the blastocyst is formed, into two layers: 
the one superficially situated, formed of flat cells with large 
nuclei, the other deeper one consisting of a cylinder epithelium. 
When the uterine epithelium has entirely disappeared, maternal 
vessels, provided with their endothelial sheath, come into con- 
tact with the superficial layer of epiblast. ‘The cell-boundaries 
of the constituent cells of this layer then disappear; the layer 
is thus transformed into a continuous mass of protoplasm with 
large nuclei distributed in it, which appear to multiply by 
direct division. This layer rapidly increases in thickness ; it 
penetrates between the vessels, pushing back the connective 
tissue, and envelops these vessels on all sides, which afterwards 
lose their endothelial layer and are converted into blood 
lacune, without any wall to themselves. Maternal blood 
circulating in these lacunz is thus in immediate contact with 
the protoplasmic nucleated jayer of epiblastic origin. .... 
When the villosities of connective and vascular tissue, partly 
formed by the somatopleura of the serous (v. Bir’s) envelope 
and by the allantois, penetrate into the epiblastic layer (which 
is already traversed by maternal blood lacune, and which is 
considerably thickened and formed of two strata, a deeper 
cylindrical and a superficial very thick one, formed by a true 
plasmodium), each of these villosities is directly surrounded 
by the cylindrical layer and as directly by the plasmodic layer 
of the epiblast. There is then a rich network of blood-lacunz 
in the thick layer just mentioned around each of these vil- 
losities.” 
This note of van Beneden shows that the phenomena that 
were noticed and described by me for the hedgehog, agree to a 
much further extent with what is noticed in Vespertilio 
murinus than he was inclined to admit at the time of the 
