172 



cells appear to be phagocytic, devouriug the degenerate cells of 

 the layer next outside ('couche épithélioïde'), he says (p. 628) 

 'les produits ultimes de la dégénérescence de la couche épithé- 

 'lioïde se trouvent au contact immédiat de la couche paraplacen- 

 'taire; on en voit entre les cellules de cette dernière, ainsi qu'a 

 'rintérieur de leur corps protoplasmique. Il semble que leur ré- 

 'sorption est due a 1'activité phagocytaire des cellules de la couche 

 'paraplacentaire'. And secondly, this layer is in its turn invaded 

 by the trophoblast, which engulfs the blood vessels. 'D'un autre 

 'cöté, Ie placenta tend a englober les troncs veineux sur une 



'éteudue de plus en plus grande On n'y trouve plus que 



'les troncs veineux définitifs Cette disparition est causée 



par la marche envahissante du plasruodiblaste.' 



Nolf has also figured a sort of phlebitis, with accompanying 

 iufiltration of leucocytes, in the veins of the placenta, which 

 recalls Maxiraow's account of a sirnilar process in the Rabbit (see 

 above). It is due, he believes, to irritation set up by the excre- 

 tory products of the embryo as they are carried away from the 

 placenta. 



Finally, Nolf corroborates Froniniel's account of the course taken 

 by the maternal blood; but with regard to the alleged formation 

 of blood-corpuscles he says (p. 623). 'Tout ce que je puis ajouter, 

 'c'est qu'il ne peut absolument pas être question d'une formation 

 'd'hématies dans Ie réseau paraplacentaire.' 



Duval's work (8) is still uncompleted; but he has described the 

 degeneration of the uterine epithelium, the formation of cyto- 

 blastic and plasmodiblastic layers, the inclusion of the superficial 

 network of capillaries in the latter, and the subsequent disappea- 

 rance of their endothelium. 



b.) Megachiroptera. 



Göhre (14) has described late stages in the placentation of 

 Pteropus edulis. 



The placenta is mesometric and discoidal; the yolk-sac is pushed 

 away from the trophoblast by the growing allantois, and sub- 

 sequeutly crumples up. 



