308 
Dr Duckworth, The histology of the 
layer as described by Siegenbeek van Heukelom are found herein. 
Moreover the view here expressed as to the identity of the several 
elements is in accord with the description of the corresponding- 
features in early human placentae as provided by Voigt*'. 
And lastly, in the Figures 9, 10, 11, the mass of embryonic 
tissue described as invading the lumen of the blocked- up uterine 
gland, resembles this outer layer, in its staining qualities, so that 
they may be regarded as identical. And it is probably on account 
of the greater mass of the tissue seen in the Figures (9 — 11) that 
the nuclei are so much more distinct here than in those regions in 
which the layer is attenuated. 
Conclusions. 
1. The specimen represents the histological conditions in an 
early stage of placental formation in Macacus nemestrinus. 
2. The decidual formation is that known as decidua compacta 
basalis, no decidua reflexa being present. The “ wall ” or circum- 
vallation described by Selenka in Seinnopithecidae is not present 
here. 
3. The uterine tissues immediately beneath the area of 
attachment of the blastocyst, and also for some distance on either 
side of this, are oedematous. 
4. Immediately beneath the blastocyst, there is even an 
accumulation of a fibrinous exudation, by which the apparently 
degenerating cells of the uterine epithelium are thrust off. These 
cells are then probably destroyed, whether by the action of the 
embryonic ectodermal cells, or by that of leucocytes escaping 
with the fibrinous exudation, or by both methods, cannot be 
ascertained. 
5. There is no evidence of the transformation of cells either 
of the uterine epithelium or of the glandular lining, into syncytial 
masses, as described by Selenka in Semnopithecus pruinosus &c., 
and by Langhans and Merttens in man. 
6. The cell-nests found by Selenka in the submucosa in the 
animals mentioned above, cannot be identified with certainty and 
are not in any case prominent objects. 
7. The evidence of the sections leads to the conclusion 
that the intervillous spaces are not lined by any derivatives of 
maternal cells, but b} 7 embryonic ectodermal cells. 
8. The epithelial lining cells of the uterine glands seem to 
play no permanent part in the formation of placental tissues. 
* Zeitsclirift fur Geburtshilfe and Gyncikologie, Band 54, 1905, pp. 66, 67. 
Cf. also Voigt, ibid. Band 51, 1904. 
