of wounds.

XIX.--The common iliac artery. When a ligature is applied to the middle
of this artery, the direct circulation becomes arrested in the lower
limb and side of the pelvis corresponding to the vessel operated on. The
collateral circulation will then be carried on by the anastomosis of the
following branches--viz., those of the lumbar, the internal mammary, and
the epigastric arteries of that side with each other, and with their
fellows in the anterior abdominal parietes; those of the middle and
lateral sacral; those of the superior with the middle and inferior
haemorrhoidal; those of the aortic and internal iliac uterine branches
in the female; and of the aortic and external iliac spermatic branches
in the male. The anastomoses of these arteries with their opposite
fellows along the median line, are much less frequent than those of the
arteries of the neck and head.

XX.--The external iliac artery. This vessel, when tied at its middle,
will have its collateral circulation carried on by the anastomoses of
the internal mammary with the epigastric; by those of the ilio-lumbar
with the circumflex ilii; those of the internal circumflex femoris, and
superior perforating arteries of the profunda femoris, with the
obturator, when this branch arises from the internal iliac; those of the
gluteal with the external circumflex; those of the latter with the
sciatic; and those of both obturators, with each other, when
arising--the one from the internal, the other from the external iliac.
Not unfrequently either the epigastric, obturator, ilio-lumbar, or
circumflex ilii, arises from the middle of the external iliac, in which
case the ligature should be placed above such branch.

XXI.--The common femoral artery. On considering the circles of
inosculation formed around the innominate bone between the branches
derived from the iliac arteries near the sacro-iliac junction, and those
emanating from the common femoral, above and below Poupart's ligament,
it will at once appear that, in respect to the lower limb, the
collateral circulation will occur more freely if the ligature be applied
to the main vessel (external iliac) than if to the common femoral below
its branches.

XXII.--The superficial femoral artery. When a ligature is applied to
this vessel at the situation where it is overlapped by the sartorius
muscle, the collateral circulation will be maintained by the following
arteries:--the long descending branches of the exte