350 A. A. W. HUBREOCHT. 
embryonic stages, even before the formation of fetal 
blood-vessels in the area vasculosa, maternal blood pene- 
trates into the deepest lacune that are in immediate con- 
tact with the yolk-sac. These lacune are for the greater 
part surrounded by embryonic trophoblast-tissue. These 
facts have been repeatedly verified by injections that were 
made from the maternal iliac artery, the specimens being 
afterwards sliced by the microtome. . . . Those of the 
lacunary blood-spaces, which in the very youngest stages 
appear to arise out of enlarged portions of maternal capil- 
laries, lose every trace of an endothelium, and are in open 
communication with the decidual vessels. . . . When the 
development of the blood-vessels of the yolk-sac is at its 
height, the circulation of maternal blood in the adjacent tro- 
phoblastic lacune is, of course, of great significance. These 
lacunze are, however, gradually reduced as the blastocyst 
increases in size, and then the lacune in the placental region 
come into the foreground. In the ripe placenta the maternal 
decidual vessels open into the lacunar system which bathes 
the network of allantoic vessels.”’ 
In these lines a very summary account was given of what is 
for the first time fully described and figured in this article. 
Continuing the historical account of the development of the 
views concerning these nutritory processes and the correspond- 
ing morphological arrangements, I may not omit the fact that 
in Wirzburg (l. c., p. 514) Ed. van Beneden expressed dis- 
agreement with my views about the trophoblast, and took 
exception to the view of maternal blood circulating in lacune 
that were bounded by embryonic epiblast. He founded his 
objections on his own observations on the bat. 
Already in the February meeting of 1888 of the Belgian 
Academy of Sciences! he had given an account of the placen- 
tation of Vespertilio murinus, in which the appearance of 
epiblastic layer of the blastocyst. This ‘non-formative’ epiblast takes an 
active part in the nutritory process intended for the embryo, and for this 
reason the name of trophoblast was chosen.” 
1 ¢ Bulletin de l’Acad. Royale de Belgique,’ ser. ili, vol. xv, p. 351. 
