No. 3.] UTERUS AND EMBRYO. 347 
than the unaltered protoplasm. Examination with an apochro- 
matic oil immersion shows in some parts of the degenerated 
epithelium a distinct network, the threads of which are rather 
coarse and hyaline in appearance. In default of chemical and 
further microscopic examination we may accept the hypothesis 
that the degeneration consists in direct change of the pro- 
toplasmic reticulum into hyaline substance, accompanied by 
thickening of the reticular threads. The degeneration of the 
epithelium has progressed much further over the non-placental 
area than elsewhere, and much less over the placental area: 
the peri-placental regions are in an intermediate stage. 
It is also important to note that the deep portions of the 
glands are nowhere degenerated. The glandular layer may be 
divided accordingly into an upper degenerated zone and a lower 
not degenerated zone. 
In the placental area there is no stretching of the tissues, and 
accordingly the glands retain their tubular character. The 
nuclei fill up most of the epithelial layer; there are three, four, 
or even five, in each cell in the upper part of the gland; the cells 
of the fundi are but slightly altered from their usual appearance. 
The embryo is attached to the maternal placental surface only 
by the ectoderm, without any participation of the other germ 
layers, direct or indirect, so far as I can observe. That portion 
of the ectoderm which is soldered to the uterus is very much 
thickened, in marked contrast to all other parts of the layer. As 
shown in Fig. 1., Pl. XXVI., the placental ectoderm runs over 
the surface only of the placenta, and stretches straight across 
the mouths of the glands, shutting them completely; it 
does not dip down into the glands at all, and possesses no villi 
whatsoever. On the surface, between the glandular orifices, 
the uterine epithelium, already degenerated, is clearly distin- 
guishable. 
In the other regions the stretching of the walls stretches the 
glands also, and of course proportionately to the extent of the 
strain ; hence, in the non-placental area the glands become slits 
running parallel to the surface, and in the peri-placental part 
become wide cavities. The upper zone of the peri-placental 
glandular layer has its epithelium changed into a very thick 
layer, and beginning to undergo resorption, as evidenced by the 
presence of cavities. As we follow round towards the non-pla- 
