smooth and glistening spots (PI. XXXV, fig. 9) which, when bisected from the
mucous to the muscular coats, give a convex profile towards the uterine cavity.
They are nearly all on a level with the general mucous surface and occur either as
larger or smaller spots involving a number of ridgelets, or are confined to one patch
not surpassing the size of three or four of the pits or crypts. In the uterus before
me, which is soft, and little, if anything,' contracted by the spirit in which it has
been preserved, the former predominate over the latter. In a square inch, taken at
haphazard from the dorsal wall of the left horn, eighteen of these spots were counted,
the largest being 0T9 inch in diameter and the smallest not more than 0-01. They are
irregularly distributed all over the mucous surface, but many are so minute that the
uterine wall must be artificially stretched to exhibit them, and it is also important to
note that when the uterus contracts many are hidden by the bringing together of
the fine ridgelets of the mucosa, so that they are liable to be overlooked. The
majority have a rounded form, and the ridgelets and fine threads of the mucosa
radiate outwards from their circumference, but some have an elongated character,
and others are irregular in shape.
In a uterus less mature than that from which the preceding description was
takp.n the smooth spots appeared to be much more numerous, but this was doubtless
due to the walls of the uterus being less expanded. I t also showed the existence
of larger bare spots than any hitherto described, but these, however, were not numerous
and had no regular distribution, and, moreover, the largest was not more than
about half an inch in extent and of most irregular outline.
When the bare spots of the ordinary character (PI. XXXV, figs. 9 and 10) were
examined with a hand-lens, the appearance as if a small orifice existed was distinctly
visible in certain lights, fig. 10, occupying the centres of many of them and forcibly
recalling one of the leading features in the structure of vthe gravid uterus of the
sow. The mucosa over these nude areas is so delicate and transparent, that with the
artificial aid just mentioned, the utricular glands underlying it were easily discernible,
As the only tubular structures present in the wall of the uterus are blood
vessels and utricular glands, and as these apparent openings are not the mouths of
blood vessels, the conclusion is forced upon us, that if they are openings they are
mouths of the utricular glands, holding the same relation to the walls of the uterus
and to the bare spots in this Cetacean, as do the utricular glands in the uterus of
the sow and in those of other uteri with a diffuse placentation that have been
recently described by those masters in this field of anatomy, Ercolani and
Turner,
Utricular glands.—When viewed under the microscope, a bare spot being
selected for observation in horizontal section (PI. XXXVIII, fig. 8) these structures
are seen to be especially numerous all around it and are very tortuous and much
branched, the branches being of various lengths, rather tending to convolute and
to increase somewhat in diameter towards their blind extremities. They sometimes
divide dichotomously, and sometimes three branches will be given off at one point,
whilst in other instances a branch will give off only one short saccule from its
side. The glands would appear to be not quite so numerous immediately below a
spot, but the careful observation of their distribution and of their relations to the
spots leads to the conclusion that, as in the. sow and in the other Mammalian uteri,
already referred to in this work, the smooth-spots of the gravid uterus of Platamsta
would seem to hold the same relations to the gland layer. Viewing the uterus with
a hand-lens I have frequently seen what appeared to be unmistakable evidence of
an opening of a gland, and in pursuing the plan of dissecting off the gland layer
from the back of such a smooth-spot I have further convinced myself of the intimate
relation of the glands to it and of their terminating in it, but under the
microscope after the examination of a most extensive series of sections I have never
yet been able to demonstrate conclusively the opening of an utricular gland in such
an area, not that we are to conclude that it is absent, but that the difficulty of
demonstrating it is great.
Chorion.—The membranes (PI. XXXIV, fig. 2) present three well-marked portions
corresponding to the three divisions of the cavity of the womb. The first is
the great sac moulded to the mucous surface of the left horn ; the second is the
sac filing the unfecundated right horn, and the third is what Professor Rolleston1 has
called the csecal extremity of the membranes from the two horns, projecting into the
short corpus uteri. When the amnionic and allantoic fluids are drawn off, the chorion
contracts into numerous rugose folds, which are very strongly marked in the right horn
and on its uterine sac, but when the allantois is filled, and the membranes are placed
in water for about half an hour, all these strong folds disappear, or slight traction
demonstrates the fact that they are temporary. They radiate from the Eallopian
poles of the chorion and from the apex of the uterine sac, but they are very feebly
marked on the left horn, which has been greatly distended by the foetus. In its
distended state, however, the chorion is marked by certain persistent folds that are
not removed by any amount of tension. When placed in water they form wavy
fringes, and the most prominent run from the uterine pouch (sp) to the angle of
union of the two horns of the chorion. In passing on to the left horn their course
is interrupted by a long linear bare patch hereafter to be described, but beyond
this point they course round the right pole of the left horn to the dorsal aspect
where they are lost. Each forms a wavy fringe about half an inch in breadth
in its broadest part. These folds radiate from the perfectly nude space as the
apex of the sacculated portion of the membrane which depends into the corpus
uteri (PI. XXXIV fig. 2, sp. and 3,) and which corresponds to the lameflarly
folded os uteri internum. This stellate bare patch (fig. 3) has a strong resemblance
to the similar area in Orca and in the mare as described and figured by
Turner. A few persistent folds oocur at the two poles of the chorion and are doubtless
adapted to the folds of the Eallopian orifices. Besides these, many fine rugose
folds encircle the left horn of the chorion, and are especially numerous and best
marked to the right of the umbilical region, where they correspond to the folds
of the-septum of the left horn, and in this region they spring from a linear bald
1 Trans. Zool. Soc., Vol. V, 1866, p. 307.
o 3