THE ORNITHORHYNCHUS PARADOXUS. 239 
stem of grass, not much larger in diameter than a hog’s bristle, to pass through it ; just 
within the orifice were two small raised reddish bodies, the use of which I do not know. 
The interior coats of the uterus were corrugated and of a fine pinkish colour. 
On laying open the right uterus, although it was also enlarged and had some degree 
of vascularity, with ovaries on its upper part, no eggs were found within: internally 
it had the same corrugated appearance as was observed in the left, but the vascular 
tinge existed in a less degree. 
The cheek-pouches, or, as I am inclined to consider them, the first stomachs, of both 
stratum: but the theca, or innermost parietes of the sac, was much thickened, and encroached irregularly upon 
the empty space, so as to leave only a cylindrical passage to the external opening. * * * * 
“The two smallest sized ova * * * were situated at the upper part of the left uterus, and at the distance of 
about a line from each other, Each ovum was spherical in form, and measured two lines and a half in diameter : 
they were of a deep yellow colour, with a smooth and polished surface, and had not the slightest adherence to 
the uterine parietes. 
“The two ova next in size * * * measured each three lines in diameter, and were situated a little below the 
middle of the left uterus : they were of aspherical form, but had evidently been slightly compressed in the uterine 
cavity. They were of a lighter colour than the preceding, a circumstance which was specially evident at the 
upper part, from the subsidence of the contained vitelline mass. Externally they were smooth, and rolled 
freely out of the position where they were lodged like those of the preceding specimen. 
“The largest ovum * * * had the same spherical form, smooth exterior surface, and freedom from connexion 
with the uterus, as the preceding, but was of a much lighter colour, owing to the increased quantity of its fluid 
contents, to which its greater size was chiefly attributable. It measured three lines and a half in diameter, 
and had been situated in a depression or cell a little below the middle of the left uterus. The lining membrane 
of the uterus was highly vascular in the recent state in each of the above specimens. 
“In all these ova the contents could be seen, through the cortical or outer membrane, to be of two kinds, 
viz., a greyish subtransparent fluid and a yellowish denser mass, which varied in their relative proportions as 
above mentioned, the denser substance always subsiding to the lowest part of the ovum, whichever way it was 
turned. In the largest ovum, the yellow mass or yolk occupied about one third of its cavity, while in the small- 
est it constituted four fifths of the whole mass. 
“The chorion or cortical membrane of these ova offered a moderate degree of resistance when torn open with 
the forceps, and yielded equally in every direction when Separated from the yolk, the rent margins curling in- 
wards like the coats of a hydatid. This membrane was of a dull greyish colour inclining to brown, slightly trans- 
parent, and more polished upon its inner than upon its outer surface: it resembles the cortical membrane of 
the ovum of the Salamander, but is of a more delicate texture. The fluid contents occupied the space between 
the cortical and yitelline membranes, a situation analogous to that of the albumen in the egg of the Fowl, 
but had not become coagulated by the action of the spirit in which the ova had been so long immersed. 
“The yellow matter, or yolk, was seen to be invested by its proper capsule, which, when reflected under 
the microscope, was found to consist of an extremely thin, smooth, and transparent outer layer, which I regard 
as the membrana vitelli, with a thicker granular membrane immediately lining it, analogous to the blastoderma 
or germinative membrane. The contents of the above investments, or substance of the yolk, consisted of innu- 
merable minute opake granules, similar in size and regularity of form to those contained in the ovarian follicles, 
and with these granules were mingled larger transparent globules of oil. There was not the slightest trace of 
chalaze attached to the vitelline membrane, as, from analogy, we should expect to be the case had the ovum 
been destined to have been perfected by incubation. I was unable to detect any rudiments of the embryo,” — 
Philosophical Transactions for 1834, p. 555. 
