

PLACENTATION OF THE SEALS. 291 
These cells rested on a delicate sub-epithelial connective tissue in which the 
maternal capillaries ramified. The trabecule and the sub-mucous connective 
tissue were carefully examined, with the object of ascertaining their relations 
to the tubular glands. In vertical sections the glands were distinctly seen, trans- 
versely or obliquely divided, lying in a definite layer of connective tissue situated 
under the crypts. Sometimes the divided glands were separated by comparatively 
broad bands of connective tissue from the crypts and trabecular structure, but 
in other places they were immediately subjacent. They were lined by a well- 
defined columnar epithelial layer (fig. 11). I looked for the stems of the glands to 
see if I could ascertain whether they opened into the crypts or passed along the 
trabecule to open on the free surface of the mucosa, but did not succeed in 
tracing them to their orifices. 
As it was important, however, to ascertain if the crypts equalled in 
number in a given area the glands of the mucosa in the same area, or if 
the crypts much exceeded in number the glands, I submitted different parts of 
the mucosa of the gravid uterus of this cat to microscopic examination, and 
compared the appearances seen with those presented by the mucosa of the 
non-impregnated uterus. In the non-gravid cat the stems of the glands were 
almost perpendicular to the free surface of the mucosa. They were so tortuous 
at their deeper ends as to be repeatedly cut across in a vertical section through 
the membrane. The inter-glandular connective tissue, containing numerous 
corpuscles, formed well-marked bands between the glands. Vertical sections 
made through the mucosa lining the constrictions between the compartments of 
the uterus of this gravid cat showed the tubular glands to be on the average ith 
wider than in the non-gravid condition; the inter-glandular connective tissue 
was much smaller in quantity, so that the glands were more closely crowded 
together; but in the placental area of the mucosa of the same cat the inter- 
glandular tissue was greatly increased in quantity, so that the glands were 
further apart, and, as in the non-placental area, dilated: but the number of 
glands seen in the sections did not nearly equal the number of crypts. 
In a cat’s ovum, which had reached a somewhat more advanced stage of de- 
velopment, where the long diameter of the uterme compartment, measured, along 
the arc, was 14 inch, I found that the villi of the chorion readily disengaged from 
the uterine crypts. By far the larger part of the chorion was still villous, not more 
than +2,;ths inch at each pole being smooth. The line of demarcation between the 
placental and non-placental polar areas of the mucosa was very distinct. The 
placental area, or the hypertrophied and spongy mucosa, possessed a reticulated 
appearance, the principal strands of which were sinuous, and gave off numerous 
collateral branching offshoots, which joined adjacent branches to form the walls of 
the numerous pits or crypts which opened on the surface. The strands and 
branches were larger, and the pits and crypts were more dilated than in the 
VOL, XXVIII, PART III. 4G 
