388 Maximilian Herzog. 



eating spaces contained in a network of irregular bands, strands and 

 masses of trophoblast material. The cavities in the trophoblast are 

 not empty, but well filled with maternal blood. There is a certain 

 regularity of those trophoblast cavities which are situated next to 

 the chorionic cavity. Here they are somewhat regularly cuboidal 

 and they are jolaced around the chorion mesoderm like blocks 

 of stone in a pavement. It is evident that this arrangement is 

 brought about by two factors working in a certain sense against 

 each other, namely, the pressure of the maternal blood and the 

 growth energy of the chorion mesoderm. Towards the chorion meso- 

 derm, these cavities are lined by a thin layer of trophoblast, com- 

 posed of one cell layer of the "Grundschicht" and one layer of 

 ''Deckschicht" or syncytium. Towards the periphery these cavi- 

 ties are lined by more powerful masses of trophoblast. In the middle 

 stratum of the trophoblast there are irregular cavities of moderate 

 size, and in the outer stratum the open, blood-containing spaces be- 

 come very large and very irregular. In this outer zone we find the 

 trophoblast material much diminished, and where it is in con- 

 tact with the thin capsularis, it dwindles down to isolated thin 

 threads or pillars of cells. 



The cells of the ''Grundschicht," or that part of the trophoblast 

 which later becomes the Langhans layer of the villi, are most char- 

 acteristic in the middle zone where they are present in the shape 

 of bands and beams and irregular masses, and where they have 

 not been exposed to considerable pressure, as in the zone next to 

 the chorionic cavity. In the middle as well as in the outer zone 

 the cells have the following characters : The protoplasm is generally 

 almost si^herical, or in consequence of mutual compression of the 

 cells irregularly polygonal. The cell boundaries are so very distinct 

 that it appears as if the cells had membranes. The protoplasm has 

 stained very lightly with eosin and gives the impression that the 

 cells "inter vitam" must have been very "saftreich." The nuclei 

 are large, round and vesicular, with a finely granular chromatin 

 network. Frequently one or occasionally two nucleoli can be seen ; 

 these likewise are more or less distinctly vesicular in appearance. 

 The nuclei are about twice the diameter of the maternal red blood 



