THE SYNCYTIUM. 65 



cells of the dilated decidual blood vessels and the epithelium of 

 the glands. A detailed report of his findings is still outstanding. 



V. 

 THE SYNCYTIUM. 



In the previous chapters, in describing the ectoblast and tropho- 

 blast, mention has so frequently been made of the syncytium 

 that no doubt can be left concerning my own views of its origin. 



Since the opinions of most prominent investigators- are still 

 at variance on this point, I shall once more consider the origin 

 and function of the syncytium and shall quote disparaging views 

 of others. 



In accordance with Peters, my specimens (Figs. 16 and 17) 

 show that the syncytium forms the external cell layer of the 

 ectoblast and that it is first noticed in this situation. We have 

 further observed that when the inner layer of cells (Langhans' 

 cells) begin to send out small excrescences (Fig. 17 kn.) or 

 longer processes, (Figs. 16 and 17 tr) these are covered with 

 syncytium which closely follows all the larger and largest tropho- 

 blast columns and with them reaches the connective tissue of the 

 ovular chamber. 



In this manner the syncytium separates all the proliferations 

 of the trophoblast from the surrounding blood. 



Next it becomes the duty of the syncytium to connect the ends 

 of the trophoblastic processes with the adjoining tissue, to corrode 

 the surrounding vessels, to unravel their walls and finally to 

 open up more and more blood spaces from which the growing 

 ovum may derive its nutrition. 



. In all specimens thus the syncytium can be followed from with- 

 in outwards, from the ectoblast towards the ends of the tropho- 

 blastic processes, but not in the reverse direction. It can be 

 observed at the ends of the short trophoblastic excrescences, 

 which have not as yet become adherent, in form of those well 

 known processes which vary in shape but as a rule are knob- 

 like. In studying these pictures and comparing them with others 

 it seems impossible to come to any .other conclusion than that 

 the syncytium is solely of fetal origin and that it forms the ex- 

 ternal cell layer of the ectoblast providing for the growth and 

 nutrition of the ovum. 



The manner also in which the syncytial cells corrode, weaken 

 and dissolve the vessel walls, leads us to but one conclusion, viz : 

 that they must be fetal tissue originating in the Eianlage. One 

 can see how thev leave the ovum and advance into the tissue 



