horacic walls, directly into the distended
pericardium, for the escape of its fluid contents, if such proceeding be
in other respects deemed prudent and advisable.

The abdominal cavity being very frequently the seat of dropsical
effusion, when this takes place to any great extent, despite the
continued and free use of the medicinal diuretic and the hydragogue
cathartic, the surgeon is required to make an opening with the
instrumental hydragogue--viz., the trocar and cannula. The proper
locality whereat the puncture is to be made so as to avoid any large
bloodvessel or other important organ, is at the middle third of the
median line, between P the umbilicus, and Z the symphysis pubis. The
anatomist chooses this median line as the safest place in which to
perform paracentesis abdominis, well knowing the situation of 2, 3, the
epigastric vessels, and of Y, the urinary bladder.

All kinds of fluid occupying the cavities of the body gravitate towards
the most depending part; and therefore, as in the sitting or standing
posture, the fluid of ascites falls upon the line P Z, the propriety of
giving the patient this position, and of choosing some point within the
line P Z, for the place whereat to make the opening, becomes obvious. In
the female, the ovary is frequently the seat of dropsical accumulation
to such an extent as to distend the abdomen very considerably. Ovarian
dropsy is distinguished from ascites by the particular form and
situation of the swelling. In ascites, the abdominal swell is
symmetrical, when the body stands or sits erect. In ovarian dropsy, the
tumour is greatest on either side of the median line, according as the
affected ovary happens to be the right or the left one.

The fluid of ascites and that of the ovarian dropsy affect the position
of the abdominal viscera variously In ascites, the fluid gravitates to
whichever side the body inclines, and it displaces the moveable viscera
towards the opposite side. Therefore, to whichever side the abdominal
fluid gravitates, we may expect to find it occupying space between the
abdominal parietes and the small intestines. The ovarian tumour is, on
the contrary, comparatively fixed to either side of the abdominal median
line; and whether it be the right or left ovary that is affected, it
permanently displaces the intestines on its own side; and the sac lies
in contact with the neighbouring abdominal parietes; nor will the
intestines and it change position accor