should be kept as clean as
possible, and any escaping blood should be mopped up with the cotton or
the sponge. The dissection is best carried out by observing the following
order:

1. Cut through the abdominal wall in the center of the triangular space
where the ribs converge. From here cut a slit downward to the lower
portion of the abdomen, and sideward as far as convenient. Tack the
loosened abdominal walls to the board, and proceed to study the exposed
parts. Observe the muscles in the abdominal walls, and the fold of the
_peritoneum_ which forms an apron-like covering over the intestines.

2. Observe the position of the stomach, liver, spleen, and intestines, and
then, by pushing the intestines to one side, find the kidneys and the
bladder.

3. Study the liver with reference to its location, size, shape, and color.
On the under side, find the gall bladder, from which a small tube leads to
the small intestine. Observe the portal vein as it passes into the liver.
As the liver is filled with blood, neither it nor its connecting blood
vessels should be cut at this time.

4. Trace out the continuity of the canal. Find the esophagus where it
penetrates the diaphragm and joins the stomach. Find next the union of the
stomach with the small intestine. Then, by carefully following the coils
of the small intestine, discover its union with the large intestine.

5. Within the first coil of the small intestine, as it leaves the stomach,
find the _pancreas_. Note its color, size, and branches. Find its
connection with the small intestine.

6. Beginning at the cut portion of the abdominal wall, lift the thin
lining of the peritoneum and carefully follow it toward the back and
central portion of the abdomen. Observe whether it extends back of or in
front of the kidneys, the aorta, and the inferior vena cava. Find where it
leaves the wall as a _double_ membrane, the _mesentery_, which surrounds
and holds in place the large and small intestines. Sketch a coil of the
intestine, showing the mesentery.

7. Find in the center of the coils of small intestine a long, slender body
having the appearance of a gland. This is the beginning of the _thoracic
duct_ and is called the _receptacle of the chyle_. From this the thoracic
duct rapidly narrows until it forms a tiny tube difficult to trace in a
small animal.

8. Cut away about two inches of the small intestine from the remainder,
having first tied the tube on the two sides of the