162 



directly transfornietl iuto the vesicular cells which he finds occur- 

 ring abuudautly in later stages on the maternal side of the pla- 

 centa, and dipping down as 'ïlots vésiculeux' into the allantoic 

 portion (see his Figs. 139, 147, 148, 150, 154, 163). In these 

 drawings 'vesicular' cells are figured which are clearly what I 

 have called trophoblastic glycogenic cells; and these cells appear 

 to me to fiud their real representatives, in his figures of earlier 

 stages, not, as he supposes, in the stellate and fusiform cells just 

 alluded to, but in a layer (Figs. 132, 133) which he has des- 

 cribed (p. 356) as 'une couche (qui) présente 1'aspect d'une sub- 

 'stance homogene parsemée de lacunes sanguimaternelles'. He 

 says that it is transitory, becoming transformed into the 'couche 

 réticulée' of the region below ; but it corresponds exactly in po- 

 sition, and very fairly in appearance to the layer of trophoblast 

 immediately external to the allantoic portion of the placenta, 

 before glycogenesis has set in in it. 



This interpretation of Duval's description and figures renders 

 it comparatively easy to account for another serious error into 

 which, as I believe, he has fallen. He bas described, under the 

 title of 'formation plasmodiale endovasculaire', an ingrowth of 

 trophoblast iuto the maternal blood vessels, an ingrowth which 

 gradually creeps up the sides of the vessels, destroying the endo- 

 thelium in front of it, and encroaching on the intervascular con- 

 nective tissue. I must say that I have never seen any thing at 

 all resembling what he has drawn in Figs. 158, 159. Looking 

 however at the figures drawn under a lower power (Figs. 147, 

 148) it seems to me obvious that his 'endovascular plasmodium' 

 is nothiug else but the lining of a trophoblastic sinus in the 

 upper, glycogenic, portion of the placenta. In other words he is 

 absolutely correct in altributing an ernbryonic origin to the cells 

 which form the lining of these cavities, totally incorrect in 

 regarding the cavities themselves as maternal. These blood spaces 

 are, in his figures separated from one another by masses of 

 'vesicular' cells; and it is clear that, having derived these cells 

 from subepithelial tissue, he feit bound to regard the blood 



