early placenta of Macacus nemestrinus. 
309 
Before they meet any embryonic tissues, the gland cells may be 
largely destroyed through haemorrhage into the gland-cavity or 
lumen. When the glandular epithelial cells do meet the embryonic 
cells, they seem to be destroyed while the latter persist. 
9. Two varieties of embryonic ectodermal tissue take part in 
these processes. They are (i) the outer, more deeply stained and 
in places discontinuous masses, identified in the description with 
the syncytial tissue (Plasmoditrophoblast of the writers on this 
subject) : and this tissue does not seem to play a permanent part 
in the placental formation, though it may invade capillary vessels 
and uterine glands. It seems to determine the opening up of 
communications between the maternal capillary vessels and the 
intervillous spaces, (ii) The other tissue is identified with Voigt’s 
Grundsehicht of the villous processes (? Cytotrophoblast of other 
authors) and this is the tissue which has permanent relations in 
the placenta as ultimately constituted. 
10. The absence of mesodermal tissues (embryonic) from the 
villi indicates the early stage of development here described. At 
the same time, this absence renders difficult the identification of 
various tissues in the embryonic villi. 
DESCRIPTIVE NOTES TO FIGURES. 
Fig. 1. Section 116 (x 16). The remaining portions of the blastocyst 
project from the uterine wall into the uterine cavity. Villi and 
intervillous spaces are shewn. 
Fig. 2. Section 293 (x 16). The general appearances resemble those in 
Fig. 1. Here a moi’e distinct placental area is seen. The glands 
are rather more numerous. 
Fig. 3. This is a schematic l’epresentation of the probable conditions 
obtaining in the specimen before part of the blastocyst had been 
removed. The latter structure projects into the uterine cavity. 
The thick trophoblastic layer is shewn. The figure is based upon 
those pi'ovided by Selenka (for references cf. text). 
Fig. 4. Section 45. Obj. §. Oc. No. 2 (x4). Camera lucida, Leitz. 
The blastocyst is not here actually attached to the uterine wall 
over which the epithelium still forms a continuous covering. The 
uterine tissue is oedematous, and in places a fibrinous exudation 
has been poured out beneath the epithelium. 
