PLACENTATION OF THE SEALS. 283 
the glands, and the proportion of interglandular connective tissue was almost 
alike on both aspects. 
From a comparison of the mucosa of the gravid with the non-gravid horn of 
the pregnant uterus, and of these with the unimpregnated uteri in these seals, 
it is evident that the changes which take place in the mucous membrane, in con- 
nection with the great distension of the uterus during pregnancy, consist in an 
obliteration of the strong longitudinal folds of the mucosa; in a large increase 
in the absolute and relative amount of the interglandular part of the mucous 
membrane ; in an elongation of the tubular glands, which elongation is in great 
part due to an untwisting of the glands, so that they become much less tortuous, 
though from the very considerable length which some of these glands possessed, 
it is possible that they and their branches may have actually grown in length. 
‘The similarity in the appearance of the septal mucous membrane on its two 
aspects was evidently due to the growth of this partition being equal for the 
non-gravid as for the gravid horn. 
The band of mucous membrane reflected on to the border of the placenta 
was smooth on its free surface like the adjacent part of the uterine mucosa with 
which it was continuous. When peeled off the placenta, and placed under the 
microscope, utricular glands were seen in it, which in form and relative numbers 
closely corresponded with the arrangement just described in the mucosa of the 
non-placental area of the gravid horn. Many of the glands, however, displayed 
an appearance such as I had not previously observed ; for their lumen, instead 
of being empty, was occupied by a bright yellow material. It is not improbable 
that this yellow substance was the secretion of the gland confined within the 
lumen through some obstruction near the mouth of the gland, which prevented 
its excretion. 
I then proceeded to examine the structure of the mucosa, the general arrange- 
ment of which, and relations to the uterine wall and placenta, have already been 
described. In the non-deciduous serotina, 7.e.,in the layer of mucous mem- 
brane left on the wall of the uterus, after the placenta was peeled off, utricular 
glands were seen, but they were much more sparingly distributed even than 
in the mucosa of the non-placental area of the gravid horn. In various of these 
glands an appearance was observed, indications of which had also been seen in 
some of the glands both in the mucosa of the non-placental area and in the 
reflexa, of a breaking up within the gland-tubes of the epithelium into scattered 
masses, separated by intermediate irregular intervals. 
On that surface of the non-deciduous mucosa, which was exposed by peel- 
ing off the placenta, irregular scattered patches of cells were seen when examined 
| with a magnifying power of 300 diameters. In some places the patches were 
| so close together that they gave the impression of being portions of the origin- 
| ally continuous epithelial layer of the mucosa, which had become broken up 
: 
VOL. XXVII. PART IU. 45 
