early 'placenta of Macacus nemestrinus. 
307 
constitute a series of bridges between the proximal and distal 
parts of the trophoblast. As has been noted already, hardly 
any of these villi contain a mesodermal core. They are solid 
columns of cells, and the appearances of these columns in 
section are represented in Fig. 12. Two varieties of tissue are 
present. Internally, large clear cells with large clear nuclei are 
seen (Voigt’s “ Grundschicht ”). Around these a layer of proto- 
plasm is wrapped. This layer stains more deeply than the central 
cells from which it is thus easily distinguishable. In its substance 
nuclei of elongated form are seen at intervals (“ Deckschicht ” of 
Voigt). 
It is tempting to regard the inner clear cells as those of 
Langhans’ layer (the term “layer” is applicable only after meso- 
blastic tissue has penetrated the previously solid rod or column of 
epiblastic cells), while the outer layer would then represent the 
“ Syncytium.” 
But while doing so, certain objections must be recognised. 
For the central cells do not in appearance reproduce those re- 
presented in the corresponding position in Selenka’s most elaborate 
drawing*. In fact as regards the relative sizes of the nuclei, the 
conditions in my specimen are exactly the reverse of those de- 
picted by Selenka. It occurs to me that the drawing referred to 
is too diagrammatic, and in fact I believe this criticism has already 
been made. 
Again, I have no evidence of cell-nests first seen in the sub- 
mucosa in stages of transition suggesting the origin of this darkly 
stained covering to the villi. But the ground is open to criticism, 
and the origin of the syncytial layer from uterine epithelial cells 
as described by Selenka f is not proved beyond doubt for the 
monkey, whatever may be the case in the rabbit. 
The outer layer is discontinuous and in places is detached 
from the underlying cells. In certain sections (cf. especially Fig. 8 
“f” and section 262) strips of it seem to be found in the path 
of the red-blood cells as they enter the intervillous spaces j. (This 
is particularly well shewn again in section 341.) But it seems to be 
diminishing in importance, while the inner cells of the villi are 
augmenting in volume and these eventually bound those parts of 
the intervillous space which are in direct continuity with the 
opened-up capillaries (Figs. 7 and 8). 
It must be admitted that the appearance of what is here 
identified with the syncytial covering of the villi, does not bear 
out the very definite account and drawings of Selenka (“ Placcn- 
taranlage ”). But on the other hand, some features of the syncytial 
* Studien, 8tes Heft, p. 100, Taf. ii. Fig. a. 
t Placentaranlage, p. 7, 1901. 
J Syncytial tissue in such situations was observed by Siegenbcck van Houkeloui, 
who suggests that they may be amoeboid {op. oil. p. 25). 
