fatal. An aneurism, as is generally understood, is an enlargement
of a certain part of an artery, this enlargement sometimes
becoming of enormous size, full of palpitating blood, and likely
to rupture with fatal results at any time. If by any means the
blood can be allowed to remain quiet for even a few hours in this
aneurism it will form a clot, contract, and finally be absorbed
and disappear without any evil results. The problem of keeping
the blood quiet, with the heart continually driving it through
the vessel, is not a simple one, and in Hunter's time was
considered so insurmountable that some surgeons advocated
amputation of any member having an aneurism, while others cut
down upon the tumor itself and attempted to tie off the artery
above and below. The first of these operations maimed the patient
for life, while the second was likely to prove fatal.

In pondering over what he had learned about collateral
circulation and the time required for it to become fully
established, Hunter conceived the idea that if the blood-supply
was cut off from above the aneurism, thus temporarily preventing
the ceaseless pulsations from the heart, this blood would
coagulate and form a clot before the collateral circulation could
become established or could affect it. The patient upon whom he
performed his now celebrated operation was afflicted with a
popliteal aneurism--that is, the aneurism was located on the
large popliteal artery just behind the knee-joint. Hunter,
therefore, tied off the femoral, or main supplying artery in the
thigh, a little distance above the aneurism. The operation was
entirely successful, and in six weeks' time the patient was able
to leave the hospital, and with two sound limbs. Naturally the
simplicity and success of this operation aroused the attention of