instances of extra-uterine fetuses, which have thus attached or inserted
their vessels into the peritoneum; or on the viscera, exactly in the same
manner as they naturally insert or attach them to the uterus.

The absorbent vessels of the embryon continue to drink up nourishment from
the fluid in which they swim, or liquor amnii; and which at first needs no
previous digestive preparation; but which, when the whole apparatus of
digestion becomes complete, is swallowed by the mouth into the stomach, and
being mixed with saliva, gastric juice, bile, pancreatic juice, and mucus
of the intestines, becomes digested, and leaves a recrement, which produces
the first feces of the infant, called meconium.

The liquor amnii is secreted into the uterus, as the fetus requires it, and
may probably be produced by the irritation of the fetus as an extraneous
body; since a similar fluid is acquired from the peritoneum in cases of
extra-uterine gestation. The young caterpillars of the gadfly placed in the
skins of cows, and the young of the ichneumon-fly placed in the backs of
the caterpillars on cabbages, seem to produce their nourishment by their
irritating the sides of their nidus. A vegetable secretion and concretion
is thus produced on oak-leaves by the gall-insect, and by the cynips in the
bedeguar of the rose; and by the young grasshopper on many plants, by which
the animal surrounds itself with froth. But in no circumstance is
extra-uterine gestation so exactly resembled as by the eggs of a fly, which
are deposited in the frontal sinus of sheep and calves. These eggs float in
some ounces of fluid collected in a thin pellicle or hydatide. This bag of
fluid compresses the optic nerve on one side, by which the vision being
less distinct in that eye, the animal turns in perpetual circles towards
the side affected, in order to get a more accurate view of objects; for the
same reason as in squinting the affected eye is turned away from the object
contemplated. Sheep in the warm months keep their noses close to the ground
to prevent this fly from so readily getting into their nostrils.

The liquor amnii is secreted into the womb as it is required, not only in
respect to quantity, but, as the digestive powers of the fetus become
formed, this fluid becomes of a different consistence and quality, till it
is exchanged for milk after nativity. Haller. Physiol. V. 1. In the egg the
white part, which is analogous to the liquor amnii of quadrup