No. 3.] UTERUS AND EMBRYO. 343 
in Boston, and their consequent high price, I have been unable 
to experiment with other methods of hardening. The speci- 
mens after hardening were for the most part stained zx ¢oto with 
alum cochineal and eosine, imbedded in paraffine and cut into 
serial sections with an automatic microtome, made by Herr G. 
Baltzar of Leipzig. 
§ 1. Uterus at six days and three hours. — The position of 
the ova is recognizable externally, being marked by a very slight 
protuberance on the free side of the tubular uterus. Transverse 
sections show that there is a considerable dilatation of the uter- 
ine cavity, corresponding to the swelling ; the walls are consid- 
erably thinned out by stretching. The glands are much altered, 
otherwise there is no striking change in the uterine structure. 
The shape of the glands varies, but everywhere their cavities 
are very much expanded, and the epithelial linings of adjacent 
glands are separated only by very thin connective tissue parti- 
tions; on the side of the mesentery the glands are distinctly 
tubular, and grouped on folds of the mucosa; the relations of 
these folds are described in the next section. On the opposite 
side of the uterus, that is, away from the mesentery, the glands 
are short, with wide cavities, constituting a series of irregular 
ampulla with wide mouths. The epithelium is thickened every- 
where ; it stains deeply, and has enlarged nuclei; it has many 
intercellular vertical fissures, and therefore a good many of the 
cells are separated from their neighbors ; adjacent cells project 
unequally, rendering the surface of the epithelium irregular. 
The change in the epithelium is greatest opposite and least 
near the mesentery, but is everywhere similar in kind, though 
varying in degree. 
I am unfortunately unable to state anything in regard to the 
relations of the ovum, owing to the failure of its attempted 
preservation in my specimens. 
§ 2. Uterus of seven days and three hours. — The placental 
swellings are well marked as smooth, rounded bulbs only a little 
larger in diameter than the unaltered uterus between the swell- 
ings, and not projecting at all on the mesenterial side of the 
uterus. Transverse sections show at once the changes which 
have taken place. As is well known, the rabbit’s uterus has six 
longitudinal folds, symmetrically disposed ; the line of insertion 
of the mesentery (mesometrium or broad ligament) corresponds 
