No. 3.] UTERUS AND EMBRYO. 373 
centa; similar appearances are clearly indicated in Ercolani’s 
memoir, 89, Tav. IV, Fig. 1, z, 2, for the Guinea pig. It is quite 
possible that the folds are more developed in the rabbit later. 
The placental glands are very much contorted, Fig. 12, g/, g/; 
very coarsely grandular, with numerous irregular vacuoles and 
with the nuclei lying for the most part against or near the outer 
surface of the gland, Fig. 13, g/: the nuclei no longer stain 
deeply as they do during the first stage of the gland degenera- 
tion, Fig. 7, In the upper part of the placenta the glands are 
much narrower and more widely separated than in the deep part 
of the layer, as can be seen in Fig. 12, which takes in about 
half of the glandular layer from the surface down ; towards the 
surface the glands often form wide loops, Fig. 12, and join one 
another, making a network with closed meshes. As regards 
the supposed foetal villi, I find the columns of the foetal meso- 
derm running down more distinctly than at thirteen days, but as 
before, the only epithelium which I clearly distinguished, is 
that in the deepest part of the glandular layer disposed as if 
covering the tips of the villi. The blood-vessels are very num- 
erous, and some of those above the glands in the foetal meso- 
derm are very large, Fig. 12, v. It will be remembered that 
these vessels belong to the foetal system and that the plexus of 
vessels, which is so conspicuous upon the surface of a freshly 
excised placenta, pertains therefore to the embryo. At certain 
points there rise thin membranes from the surface of the pla- 
centa, which carry good-sized vessels: whether these are acci- 
dental or constant, I am unable to say. Examined with a still 
higher power, Fig. 12, the glandular layer shows the peculiarities 
of its structure still more clearly; the mesothelium, mst, upon 
the surface, though composed of flat cells, has considerable 
thickness; the mesodermic cells, mes, are for the most part 
spindle-shaped and their processes anastomose; the foetal blood- 
vessels, v, v, come close against the glands, g/; if, therefore, 
there is a layer of foetal ectoderm separating the foetal mesoderm 
from the uterine tissues, it must be very inconspicuous from 
extreme thinness. 
As to the relations of the sub-placenta, my preparations are 
unsatisfactory. 
The sub-glandular layer shows the vascular endothelium ad- 
vanced in degeneration, the cells projecting far from the surface. 
