548 
PROFESSOR W. TURNER ON THE PLACENTATION OF THE APES. 
apparent boundary, though it is possible that they may have had an endothelial 
lining. They were obviously colossal capillaries dilated into small sinuses. But in 
many of the areolse, cells were intermingled with the red blood corpuscles, the nuclei 
of which were stained with hsematoxylin like the proper decidual cells. Some of 
these cells were white blood corpuscles, others of a more irregular shape were larger 
than white corpuscles, whilst others were spindle-shaped cells. They were so inter- 
mingled with the red corpuscles that they did not seem as if they had got accidentally 
amongst them in the act of making the section, but rather as if they had formed a 
portion of the contents of the sinus-like capillary, and it may have been developed 
from the white blood corpuscles. Many areolae which contained no blood corpuscles 
resembled in size, form, and general appearance those in which these corpuscles were 
situated, and without doubt must be regarded as blood sinuses, out of which the cor- 
puscles had dropped in the process of preparing the section for microscopic examination. 
But these blood spaces, though the most numerous, were not the only spaces to be 
seen in the sections ; for in the deeper part of the spongy tissue I occasionally saw 
sections through tubular structures which possessed a more or less perfect lining of 
columnar epithelium. Sometimes the cells were in position on the wall, but at other 
times they were loose in the lumen of the tube. There could be no doubt that these 
tubes were the utricular glands of the placental area ; and on the free surface of the 
serotina some rounded openings were seen, which were in all probability the mouths 
of the glands. 
In the human placenta at the fifth month the decidua serotina consisted of a 
compact cellular layer next the placenta, and of a deeper and thicker spongy layer. 
The spongy character of the latter was due to numerous areolae, which were irregular 
in form as in the earlier stages just described, but considerably larger. They were 
separated from each other by bands of decidual tissue, and though it is possible that 
some of these areolae were dilated utricular glands, a large number were unques- 
tionably the dilated blood sinuses of the decidua serotina, for they contained a red 
injection which had been passed into the uterine vessels. Bi the human placenta in 
the ninth month the serotina also consisted of a compact cellular and a spongy layer. 
It is quite certain that almost the whole, if not the whole, of the spaces in the spongy 
layer at this stage were dilated blood sinuses, for not only did they contain a red 
injection passed into them from the uterine vessels, but several of those which lay 
next the placenta had perforations in their walls through which the placental villi 
projected into the cavity of the sinus, and the sinus communicated with the maternal 
blood space in the interior of the placenta. I have obtained no satisfactory evidence 
of the persistence of the utricular glands in the placental area of the human uterus at 
and near the full time ; and in this respect my observations are more in accordance 
with those of Kolliker than with those of Friedlander, Kundrat and Engelmann, 
Langhans and Leopold, who have described enlarged but compressed glands containing 
epithelium as persisting in the placental area up to the separation of the placenta. 
